Why do a lot of people dont consider family matters a classic like the cosby show?

i mean ok first of all cosby might have paved the way for family matters but i mean family matters talked about gun violence,rasicm, and other serious issues cosby never touched on and also i loved how they would play the touching music when something sweet happened unlike cosby but i dont understand everytime someone talks about the greatest tv shows of all time you hear about cosby but not family matters why?