http://ew.com/tv/2018/01/25/why-murphy-brown-endures/

The CBS sitcom’s 10-season run from 1988 to 1998 was thanks to its ensemble, its politics, its guest-stars and, most importantly, its ability to stay relevant.

Cause she was a badarse lady.

She was ballsy. Take no prisoners.

I aspired to be her when I was a child.

The show was so good. The character of Murphy was so real. But, the show fell apart for me personally when Grant/Miles left. Still. Murphy was just a bad mama jamma.

I continued watching as long as Faith Ford was there. So a long time, for that reason...!

It stayed on because it was awesome.

The cast was superb. One of the best casts in sitcom history.

Short answer: Because of Candice Bergen's tour de force performance! I'm sure even she lost count of the number of Emmy Awards she won for Murphy Brown. Plus the rest of the cast was stellar and shared incredible chemistry.