A lot of the issues too are that the players cannibalize one another's effectiveness because of their own inabilities.
Because Kuminga can't shoot, you essentially have to run 3-4 guards with him in order to stretch the floor and/or handle the ball. That then limits lineups that Moody, TJD, Anderson, Looney etc can be in because you can't put them out there with Kuminga for extensive periods. I know these 'small lineups' have been at the center of criticism over the years, but they're a necessity for this team to function given the roster construction - that's what happens when you have bigs who can't shoot.
Spacing is king in today's NBA.
Running traditional ass lineups only works if you have the personnel to do it, and GS simply haven't had that type of personnel for years.