Then you're back in the 1800s. But we routinely look back to the 1800s to establish what is accepted practice in our government.
The number of qualifications needed in order to establish this "precedent" should tip you off that it's manufactured expressly to gain a political advantage.
Correct, no one is actually surprised that Mitch McConnell abandoned the flimsy justification for his power grab the instant it outlived its use to him.
Alternatively, McConnell could have called the vote and the Republican majority in the Senate could have just voted it down.
Pre-nuclear option (an actual example of a power grab) even a minority of Senators could stop a nominee from getting through. The Republicans had a majority.
It can't be assumed that there wouldn't be Republican defections on a Garland confirmation. This is exactly the reason the majority leader refused to allow a vote. Even now, a number of Republican Senators have already "defected" and declared they won't vote on a nominee before the 2021 inauguration.
Routinely?
This sounds a lot like "originalism", which is controversial at best.