Indeed "practice makes perfect" isn't enough. But the context being "something you enjoy", being passionate about something usually comes with self-motivation

Indeed "practice makes perfect" isn't enough. But the context being "something you enjoy", being passionate about something usually comes with self-motivation to improve and become better at something, and usually one finds a way to get better. The stagnation you mentioned is usually with people who aren't that passionate about the things they are practicing, or just using it as a means to some other ends.