Library -> Artists only shows artists that you have followed, which is a totally separate mechanism than adding songs or albums to your library. Also, I don’t see the Liked Songs option anywhere on the artist page.
I hate this stupid distinction so much as well. The idea that you have to follow artists instead of seeing the artists based on your liked songs or albums is so dumb.
Ah you're right, the artist list there is followed artists. I didn't realize that is the case.