You're super right. A lot of people get this idea that they need to start out the gate drawing perfectly, but it's that mindset that holds people back so often. Sketching and making random illustrations over and over without much direction will never get an artist to a point where they think they're good enough for a comic because they'll just keep pushing the goal.
Besides, coming from personal experience, the best thing an aspiring comic artist can do for their skills when they think they're not good enough to start is to just... go ahead and start. Lots of comic artists, both in webtoons and in professional manga/graphic novels, have improved considerably in the span of a few short years thanks entirely to their comic forcing them to frequently draw new angles and shapes. Even I'm super happy with the progress I've made in just one year since starting my comic. And if you find a comic or manga that looks perfect from beginning to end, it's because that artist had to do other comics first to get to that point. That's just part of the process.