Earlier quoted context omitted.
I use spotify in a lazy way, but essentially if I like a song, I press the check mark. If I'm doing my normal listening I just have all of my songs that are in my library on shuffle. I imagine if I hit the 10K limit this inability to use shuffle on ALL of my tracks at once would annoy me.
I only save my very favorite tracks, for full albums I add them as a playlist. That way I can still shuffle my collection of favorite awesome tracks, but I also have easy access to my favorite albums, where I still consider the whole album to be good, but only a few of the tracks stand out as absolute favorites.
I use it the same way, so for me hitting that 10K limit would take a very long time (if ever).
I can see some use cases where it would occur though.