Exactly right. That’s why the joke “There are 100 game engines written in Rust… and 5 games” is so funny. Programming nerds love the engine stuff more than the art stuff. I know I fall in to this category.
A game on the other hand is a blank sheet. There is no checklist. It's way harder to make progress on a game.
Absolutely worth it, have made lots of games in Unity just for myself that feel pretty polished, there are just so many systems to make a game work.
The advice around game engines kind of seems like "to learn how to write programs first create the compiler.
Not to say all games should be made in engines but it certainly helps.