“What’s not legitimate?”
The Electoral College. The Left wants a pure democracy, where 50%+1 get to rule over the 50%-1. They will ride this horse for the foreseeable future.
Because they assume that they will always be the ruling majority.
Safe assumption for them, since they can manufacture any votes needed to cover a shortfall. They do it all the time where they already rule.
Note well: If everybody "believes" that 50%+1 can do anything they want without limits (pure democracy), then you don't actually need 50%+1 of the people to vote your way — just make sure that everybody thinks that they did.