I was reading a comment elsewhere (https://www.lipstickalley.com/threads/for-legit-members-of-the-black-bourgeoisie-elite-upper-middle-class-was-the-cosby-show-authentic-and-relatable-to-you.6045523/post-113240980) that said that Family Ties during its first two years, was a modest hit. It wasn't until it followed (https://televisionheaven.co.uk/reviews/family-ties) The Cosby Show on Thursday nights on NBC (https://www.pajiba.com/think_pieces/how-did-it-go-so-wrong-nbcs-thursday-night-comedy-lineup-is-worse-than-its-been-in-30-years.php) that Family Ties (https://www.reddit.com/r/sitcoms/comments/1nn4e8o/was_family_ties_a_timeslot_hit_instead_of_legit/#:~:text=Lopsided_Drive_4392,%E2%80%A2%203mo%20ago) really "blew up" (https://share.google/aimode/a90ZGnPW6T2DrZ2iw) in viewership and the Nielsen ratings. But when A Different World took over (https://tvtropes.org/pmwiki/pmwiki.php/Trivia/FamilyTies) the Thursday night, 8:30 p.m. timeslot in 1987-88 (thetvratingsguide.com/search?q=1987-88) and Family Ties (https://jacksonupperco.com/2021/12/28/the-ten-best-family-ties-episodes-of-season-six/) was moved over to 8 p.m. on Sundays (https://tvseriesfinale.com/tv-show/family-ties-gary-david-goldberg-gets-the-last-word-28826/) for its final two seasons, the viewers didn’t follow and the ratings subsequently fell (https://share.google/aimode/D71moO1yoZ65qgMSe).

Even counterprogramming like Family Ties didn't do well against red hot Murder, She Wrote. Now if NBC had tried Family Ties an hour later Sundays at 9:00 it probably would have done better.

IMHO, Family Ties popularity was entirely driven by the appeal of Michael J Fox. It peaked around the same time Back to the Future opened (1985).