Did the producers make Melissa Sue Anderson's character's life so tragic that she would quit? Melissa Sue seems to hint at that in interviews.
https://www.cheatsheet.com/entertainment/little-house-on-the-prairie-the-1-cast-member-who-refused-to-show-up-to-the-cast-reunions.html/

I think that instead of firing her and the backlash that would result (most viewers didn't know about the behind the scenes MSA drama), that they decided to make Melissa Sue's miserable enough where she would quit. She said she couldn't take it any more with all the tragic events that followed Mary.

Karen Grassle, in her book, “Bright Lights, Prairie Dust, Reflections on Life, Loss, and Love from Little House’s Ma,” wrote that with the LHOTP’s two stories dealing with the sexual assault on a young girl and the deaths of Mrs. Garvey and Mary’s infant child in a house fire, “we had lost our way.” I guess Ms. Grassle agreed that those two later storylines were too intense and disturbing for the show’s many young viewers.

If you read some of the comments here, many fans have expressed that they were frightened by these two storylines when they first watched these episodes years ago.

I don't think the intention was to drive MSA away... I think that was just the result. "Sylvia" and "May We Bake Them Brown" were horrific.

And among the creepy parts of 'Sylvia' was that the teenaged girl was targetted by Mrs. Oleson for being some kind of wanton temptress who she tried to have expelled when ALL poor Sylvia did was change her clothes in her own house without knowing that the teen boys were sneaking peeks at her- yet even father-of-four-girls Charles excused the boys' intrusiveness.

And among the creepy parts of 'Sylvia' was that the teenaged girl was targetted by Mrs. Oleson for being some kind of wanton temptress who she tried to have expelled when ALL poor Sylvia did was change her clothes in her own house without knowing that the teen boys were sneaking peeks at her- yet even father-of-four-girls Charles excused the boys' intrusiveness.

It was a crazy episode, for sure.

In a LHOTP illustration of the old saying, “The road to Hell is often paved with the best of intentions,” if Charles Ingalls had left the irrepressible Albert back in that city and returned to Walnut Grove with only his wife, Caroline, and his other children, than Albert and that other callow kid would not have been there, smoking that pipe in the basement of that school/residence, resulting in the tragic, fiery deaths of Mary’s baby and Mrs. Garvey.

And, maybe I’m being too harsh, but I thought that Mr. Garvey, Charles and Caroline, Laura and especially Mary’s husband, Adam, were just a little too quick in forgiving Albert for that incredibly irresponsible act. We all know how absolutely devastated Mary was by the loss of her child. They all seemed to almost blithely accept such an awful event and life went merrily on in Walnut Grove.

I don’t know how Albert or that other boy could have coped with having to live for the rest of their lives with that feeling of enormous guilt in having caused the horrific, albeit unintentional, deaths of Mrs. Garvey and Mary’s baby as a result of their carelessness?

This LHOTP episode reminded me of a fire at a dormitory at Seton Hall University in South Orange, NJ in 2000. Three students were killed and over fifty other students, police officers and firemen were injured as a result of the fire. One young woman, a student at Seton Hall University, was seriously burned as she courageously alerted other students to the rapidly spreading fire. The subsequent accounts in the Newark Star-Ledger of this young woman’s recovery from her horrific burns were both inspiring and gut-wrenching to read. The cause of this tragic fire was the result of two drunken SHU students lighting a paper banner in a dorm hall, in order to set off the smoke alarms and “punk”everyone in the dorm. Tragically, the dorm did not have automatic fire sprinklers, which may have saved those three students.

The idiots who started the fire were eventually convicted of third-degree arson and spent a minimal amount of time in a youth correctional facility. As a result of the tragic fire, legislation to require fire sprinkler systems in all college dorms was passed.

I wonder if the two jerks responsible for that deadly Seton Hall University fire still feel any remorse for their irresponsible actions of twenty-two years ago, much like the irresponsible actions which Albert and that other brat caused on LTHOP?

I agree some of the episodes didn't seem needed. they seemed tragic just for the hell of it. a little over the top. and the Sylvia episode was just weird and creepy. It had the makings of a great story where she is rescued from that hell and becomes Albert's girlfriend and a regular on the show. that would have been great. Everyone liked the character and was rooting for her and instead they kill her off. what was the point? it just left you sour.

I have to wonder if Landon was hoping that extreme tragedy themes of many of the latter season episodes would cause viewers to lose interest and the fall of ratings would lead to the show's cancellation. I'm sure most viewers were tuning in to see a miracle of Mary having her sight restored. As I re-watch many of these episodes, so many are down right downers. It really wrecks it for those who want to escape their own problems (escapism TV).

I am sure that Ms Anderson was thrilled that so many episodes were going to explore her character's blindness. However, I think it led her character into a corner because the storylines and further character development became limited. Maybe this was intentional given that it's been established that MSA and ML were butting heads as the series evolved.

Melissa Sue Anderson said in an early interview, she was such a good crier on screen and the screenwriters thought her character was so easy to sympathize with so they decided to play the pity factor to the hilt. Unfortunately, it was overdone and when it got to the house fire episode, she had enough. So she asked Landon to provide an exit story for Mary and Adam. Adam regains his vision, becomes a lawyer and they move to New York City, coming back for one more episode "A Christmas They Never Forgot.'

I was hoping they'd get around to doing an episode where Mary learns to overcome the obstacles of a blind parent by finding a way to keep the sighter toddler from wandering off when she's by herself. That would have been much more satisfying for the audience than to have the kid killed off.

As to the later seasons becoming one tragedy after the next, I definitely agree. It seemed like Landon was shooting the show in the foot on purpose because he wanted it to tank so he could go on to something else. I hated that he had the Edwards' family fall apart--Grace and Isaiah had a great relationship. I don't believe they would EVER, EVER divorce.

And why did they need to kill off the Edwards' son? SMH

He wasn't even regularly being featured since he moved away to Chicago.

And why did they need to kill off the Edwards' son? SMH

He wasn't even regularly being featured since he moved away to Chicago.

Because he asked MSA what was stuck between her butt cheeks.