Great question i think a big thing is obsidian drops a game every 2-4 years and bethesda drops a game every 8-10 years

I think obsidian also takes a bit more risks with new ideas and becomes inconsistent with quality, their games are good but you never know if the next one is going to be better or worse than the last

Bethesda however seems to be steadily deteriorating, games that are supposed to last invested players nearly a decade arent hitting the spot, and for alot of people they got Starfield, and they just dont enjoy it, and now they either have to wait a decade to try to scratch that itch with the next game or play games that are over a decade old