@ellabellafull Part of the discourse I've seen on this is related to the aging game engine. Someone argued it's basically 10 years old, more if you consider the years of development before the game launched.
That factor is blamed for many of the increasing bugs, game-breaking problems, and other stuff over the last ~ year or two. So the idea of a 'Destiny 3' assumes a new game engine, a fresh slate of sorts.