While I can only speak for myself, it is just the feeling that 5E is reaching that point, not that it has been there for the last two years or something. I still have most of my AD&D 1E books, and there is more than my 5E.
I think a part of it also is the stuff they are making isn't what some of us are asking for (maybe a minority??), so it is a bit of a let down and it just feels like they are publishing books, not to make the game "more", but only for the money (hey, who can blame them, right?).
Sure, but how much of 3.5 and 2E did you buy? Do you have all the 5E stuff? Are they proportional?
So there is a huge difference. Back in 2e and up to 4e it was 2-3 books a month. Not a year. A month. Two years ago we were begging on these forums to see more content and they’ve actually barely scratched the surface of content. Barely and people are talking about edition bloat. Five additional rules supplements plus the core books. That’s not bloat. That’s two months. No I didn’t buy all those books every month but even buying a book every month or so you still had more content in 6 months than they’ve put out for 5e and people are talking about edition bloat.
examples of additional content they could explore that aren’t just settings:
Undead book ala Mordy, Fizban and Volo. Undead races, NPCs, aberrations included, including PC options.
weapons and equipment Book that includes more rules on magic items, classes built on magic items, magic item creation by PCs. A more martial based subclasses built around using items and weapons and taking control of the battlefield like the old warlord class from 4e. Include some siege rules.
Dungeoneering supplement with classes focused on exploration and dungeoneering and expanded monsters for the dungeon, new slimes, molds, fungi, revised monsters galore.
reprints of material from the adventures like vehicles rules, seafaring rules and even campaign setting material like the stuff on the cities for those who don’t buy the adventures. If you’re going to do reprints en masse like the new Multiverse book why not?