Republicans said out loud what the Democrats tried to hide.

And part of the reason is that there was actually a fair amount of anger directed at the Biden campaign is that frontline House members in tough races felt that the Biden Oval Office staff and campaign leaders did hide Biden's lack of capability. Not just from the public, but also from most other Democratic elected officials. Even "Top Party Democrats" don't spend a lot of one-on-one time with the President - it's his own staff that sees him most - so there was a lot of resentment at Donilon, Bernal, Tomasini, and the rest of the inner circle after the debate.

Regardless, it's going to be hard for the GOP to paint this as a "palace coup" or whatever. Biden's candidacy collapsed when he forked up at the debate - something that was entirely his own doing. He couldn't continue, and the move to get him to realize that wasn't limited to "Top Party Democrats." Up and down the ballot, leadership or rank and file - everyone was concerned, and when he failed to assuage those concerns it was a broad cross-section of the party that wanted him to go (only the folks in the safest of deep blue seats were even open to the idea of him continuing).

The GOP will find it an uphill battle to argue to voters that the right thing for Democrats to do would have been to stick with Biden. That the Democrats were doing something wrong by telling him he had to step aside. The GOP was proven right, he wasn't a good choice for Democrats - and the fact that Democrats listened to what the GOP was saying isn't likely to be regarded by many voters as betraying Biden.