I don't think anyone is asking about finding novelties, but rather correcting mistakes, learning plans, learning why certain moves are avoiding, learning about typical pawn structures from openings you play, playing over master games from the openings etc.
If you keep getting bad positions to start from, the game becomes a lot harder. I don't see the logic in not devoting any time to an important aspect of the game.
Yes, focus on principles more initially, and only worry about more intensive study when this isn't working. But it surely helps confidence and on the clock if you have a general idea of which lines you want to play.
Then again, perhaps it depends how you define opening study.
really? I started as a 1200 and it won me a lot of games straight out from the opening. It was a big part in my jump of rating from 1200-1850
The advice isn't based on anything. You don't suddenly hit a point at the extremely round arbitrary figure of 2000 where it is useful, and not before. Nor do all players at the same rating have the same weaknesses in their game.
I don't see how it's a good idea to ignore any mistakes you're making and repeating in the opening until you get to a certain level.
But it's the advice along with 'only study tactics until you're 2000' that people love to give. But nobody actually does.
As fara as i know, no one has said dont correct your opening mistakes. What i mean by "studying" openings, is until youre are around 1800-2000, you realy only need to know, and understand the openings you play. No one under 1800 needs to know, or be concerned about a novelty on move 18 of the Berlin, but thats just me.