It's not about choosing which artists you like and whether you want to give money to some particular artist or not, and not even just personally refusing to give money to any artist.
It's about going out of your way to create something that gets in the way of artists getting paid, such as obscuring/eliminating an option to buy music or give money to an artist, not just from yourself alone but from other people, who might not even have such a stance, or even realize that there has been an anti-artist decision made for them.
Not even adblockers go this far, because they just remove third party ads, and artists are still free to promote their stuff in other ways (for example, on youtube, there's still stuff in description, annotations, things inside the video, etc.). A player like this removes those options from artists completely.
It's also like, not even that different on bandcamp - you can just listen to some music there and move on without buying it. Removing an option to buy an album is kind of different. Imagine if ad blocker did that to a bandcamp webpage, that would be absurd. (bandcamp doesn't even have ads though. well, depending on what you consider "advertising or promotion", maybe the whole website looks like endless promo to you, if that's the way someone looks at entertainment)