Is there a reason playlists won’t load onto watch? Is there a limit to the size of the music one can load to the Apple Watch 5?

Is my understanding that we are limited to a fraction of the memory for music on an Apple Watch 5? I am amazed that there is no mention in the specs of the watch or watches!

I must say I find it abhorrent that Apple has limited the size of music that can be loaded to the Watch. Knowing this now it would have deterred our purchase and we have the Hemes.