I have always seemed to see content that suggests its more often the UFCs fault for the inactivity, with simply not booking people enough, more than its the fighter. That could be wrong but would be interesting to know. From what I seen seems like many fighters want to fight more often.
They have a cap on pay limits aside from Jon Jones, plus champ got PPV points too, they want to introduce the same crap into boxing with that league thing, TKO are trying to get the Ali act revoked which protects fighters pay and thiss is the reason.
The B, C, D level guys are overall better now but the top end guys arent necessarily. Around 15 years ago the UFC had Brock, Shogun, Anderson Silva, GSP and BJ as champs simultaneously. Meanwhile Aldo was champ in WEC, Overeem was champ in Strikeforce, Fedor was still on his unbeaten run etc etc. We are talking four different guys who to this day are often considered the best ever at their weight, all active at the same time and in or around their primes. I feel like every division from 170 and up right now is pretty meh.