A May 2020 article from Closer Weekly takes a fresh look at York's departure from the show. Some very nice comments about Elizabeth and Dick York.

https://www.closerweekly.com/posts/heres-what-happened-to-bewitched-star-dick-york/

“As the show progressed, more and more problems showed up. Dick was the teeniest bit chubby in the beginning, and he began to lose weight. There were episodes where they had to limit what he was doing, because he was too stoned on pills to really function well. When the show went to color, they had to heavily make him up, because he looked ill. He was pale, losing weight, getting lines in his face and they began to have to use a bronzer on him to make his face look healthy. They had to supplement the suits he was wearing, because he was still losing weight and not looking well. He even began to slouch. Rehearsals became problematic because Dick was out of it. Elizabeth and Bill really loved Dick and felt that as long as they were able to continue working with him and producing the show on time, he was worth the trouble. Elizabeth liked him personally as a human being and she loved working with him.”

And his departure:

"Unfortunately, this was one promise that couldn't be kept (not firing York in season 5 after his seizure). Explains Geoffrey, “Elizabeth said to Bill, ‘I can’t deal with this anymore.’ Even she had had enough. As long as he was doing his job, they wanted to keep and help him. Elizabeth said, ‘We have Erin Murphy on the set, a child who should not be exposed to this. If our children show up on a set, they should not be exposed to this. And I don’t think we’re doing him any big favors. He also has his own children and by pretending there’s no problem, we’re not helping him or his problem.’ So Liz put her foot down and said he’s out."

A May 2020 article from Closer Weekly takes a fresh look at York's departure from the show. Some very nice comments about Elizabeth and Dick York.

https://www.closerweekly.com/posts/heres-what-happened-to-bewitched-star-dick-york/

“As the show progressed, more and more problems showed up. Dick was the teeniest bit chubby in the beginning, and he began to lose weight. There were episodes where they had to limit what he was doing, because he was too stoned on pills to really function well. When the show went to color, they had to heavily make him up, because he looked ill. He was pale, losing weight, getting lines in his face and they began to have to use a bronzer on him to make his face look healthy. They had to supplement the suits he was wearing, because he was still losing weight and not looking well. He even began to slouch. Rehearsals became problematic because Dick was out of it. Elizabeth and Bill really loved Dick and felt that as long as they were able to continue working with him and producing the show on time, he was worth the trouble. Elizabeth liked him personally as a human being and she loved working with him.”

And his departure:

"Unfortunately, this was one promise that couldn't be kept (not firing York in season 5 after his seizure). Explains Geoffrey, “Elizabeth said to Bill, ‘I can’t deal with this anymore.’ Even she had had enough. As long as he was doing his job, they wanted to keep and help him. Elizabeth said, ‘We have Erin Murphy on the set, a child who should not be exposed to this. If our children show up on a set, they should not be exposed to this. And I don’t think we’re doing him any big favors. He also has his own children and by pretending there’s no problem, we’re not helping him or his problem.’ So Liz put her foot down and said he’s out."

Sounds like the article does it's best to exonerate Montgomery. It's clear she was not as patient as is being portrayed here.

I thought that Mr. York's time with the show ended when he had a horrible collapse onset that resulted in him being hospitalized and he asked to be gone long enough to recover but Mr. Asher let him go altogether (although this may have been due to his back issues becoming so debilitating that the insurers may not have believed they could have covered him for the show)- NOT due to Miss Montgomery saying he needed to go.

I thought that Mr. York's time with the show ended when he had a horrible collapse onset that resulted in him being hospitalized and he asked to be gone long enough to recover but Mr. Asher let him go altogether (although this may have been due to his back issues becoming so debilitating that the insurers may not have believed they could have covered him for the show)- NOT due to Miss Montgomery saying he needed to go.

I think Montgomery wanted him to go, but the production company realized he was too important to the show to fire.

And when York's health declined, and he was ultimately forced to leave, Montgomery was happy to let that happen, because she wanted to get rid of him anyway.

I think Montgomery was threatened by how important to the show York was. And because of that, didn't like him. There were probably other reasons involved, of which we'll never completely know. But at the end of the day, I believe Montgomery was classless in the way she treated York.