Two lines of thought on this:
1. After Berman took over the ST franchise, it was not uncommon for people--whether writers or Berman himself--to say less than favorable things about TOS or GR. I considered this a petty attempt to make "his" (Berman) ST the jewel in the crown (we see where that went).
2. GR was a sexual deviant who abused his position. That much was always clear. To that end, no, not every producer engaged in that sort of thing in the period, so this is a matter of no self responsibility, rather than industry culture.
Furthermore, without an ounce of shame, he allowed the myth of the "Great Bird" to take flight (no pun intended) in the early years, to the point where he was seen as THE mastermind, with everyone else being the happy minions running around the studio making contributions
(see Stan Lee's 60s/early 70s print interviews & convention appearances for similar acts of self-promotion, then see the decades-long replies from Kirby, Ditko, et al.).
What does this say? GR was not a saint, or the good-guy crusader he was made out to be--at least not to the fanboy extremes copy/pasted in innumerable publications in the 70s and 80s.
With all of that said--and in full appreciation of the many talents behind TOS--GR was the one with the spark of invention (some say intellectual theft here and there) which gave life to Star Trek
, and that's as much credit as he deserves without Crazy Gluing the positives of his creative side to the whole of his personality / inner demons.