It must apply to lower rated players because he reportedly offered it in his book "Chess Fundamentals".
I couldn't find the actual quote in the book but he does start off the book by teaching endgames- rook and king versus king mate; the two bishops mate before offering anything else.
/ Have you read it? Versions of it are in the public domain.
https://www.google.com/books/edition/Chess_Fundamentals/7UjuRfrq5bIC?hl=en
Capablanca's knowledge of openings wasn't good at the beginning of his carreer. See Corzo - Capablanca, Havana match (8) 1901, Vienna Gambit. Endgames are easier to set up for study. Recognizing what endgame you're going to have and understanding it will enable you to win. You might be able to steer the game into the endgame you want by the exchanges you make. That makes the middlegame make more sense. Each endgame only has a few percentage points of occurrence so you might find them tedious. But they're definitely worth knowing. Much more effective investment of time studying than openings
I saw a quote from Capablanca. He strongly suggesting studying the endgame before openings and the middle game, because you don't know how to open or play middle game unless you are planning coherently for the end game. Does his advice hold for lower level players (800-1200 Chess.com rating)?