I am a fan of Khabib, but it is WAY too early.
Regarding comparing different eras, certainly the level of competition has gone way up, but so has the level of coaching.
Guys like Gracie, Severn, Shamrocks, etc didn’t fight many all-around fighters but they also didn’t benefit from getting coached by the MMA minds that exist today.
Make the mistake, the game has changed TREMENDOUSLY and it’s not just the level of fighters. Modern top level camps are well funded and have it down to a science. Stuff like transitions, set-ups, ground defense, ground offense, etc are all being taught at a very high level.
There is no such thing as specialists anymore. Even fighters that are considered to be one-dimensional are only that relative to their peers. Edson Barbosa, for example, the guy is known as a pure striker, but I bet he can walk into any BJJ school and roll with the top guys. Volkov is another such example, pure striker who more then held his own on the ground vs a BJJ master Werdum.