Yes, Rats with brains knew. But rats without brains hadn’t know before and were their largest voting block. Their brainless trust had been their chief political asset. That trust’s removal leaves many too dazed to vote and some shifting to the suddenly more trustworthy Trump.
Notice that the 25th amendment was not designed to bail out politicians who spent four years covering up for their incapacitated President.
It was designed to deal with new information that required immediate action.