* There was an extremely long period of *Savage Hulk* (The standard, Hulk smash guy) not existing. From Roughly #270 to *447!* The only time we see Hulk himself are brief interventions of Nightmare controlling him, and then when he resurfaces in Banner's mind, with Fixit, leading to Professor Hulk. And from 447 to 460, he's dying of dimensional-cancer, so he's not at his normal strength level. Professor Hulk is the same strength level as Savage, as is Mindless, but both also had significant periods of being weakened (Shattered Hulk, Mindless vs the Avengers) or just not getting feats (Professor in the Pantheon, Mindless in the crossroad worlds). Then, there's two long periods of Hulk not being around due to ALS, and then Hypnotized Hulk, being weaker, and then Planet Hulk, also weaker.

* Hulk has had significant powercreep, especially with *Planet Hulk* and later books. Peter David is a good cut off point.

* Hulk got new powers from David's run and onwards (Regeneration, evolution), different takes on the character along with significant fleshing out of his existing powerset (such as astral senses).

* With Hulk feats being divided so much already (Green Scar, World War Hulk, Worldbreaker, Savage, Fixit, Mindless, Intelligent, Hypnotized, etc) it makes more sense to divide old feats from modern ones. This also makes the modern RT less cumbersome, and essentially gives a whole new character with a different powerlevel that can be used.

* Peter David's beginning of Hulk coincides with the end of the Bronze Age (With David's run starting 2 years after the end of the Bronze Age, 1985)