Youtube remains my #1 music app, regardless of sound quality, which i agree could use improvement.
The thing is, youtube has what no other music site will ever have, tons of user uploaded content. other platforms are dependent on licensing and rights agreements and record labels etc, but on youtube i can find infinitely more obscure, rare, independent, unlicensed music. when i make a playlist on youtube, and try to duplicate that playlist on spotify or apple, i can usually only find 60 or 70% of the songs on those apps.
second, as you mention, video. the whole thing with youtube is that it's fun. when you have friends over and you all take turns queuing up a song/video on youtube and it's just a very social thing, almost like a party game, you're never going to have that experience with spotify.
i absolutely wish that by some magic all the music on youtube was super high quality, but given that anyone can upload virtually anything they want regardless of quality, that would be near impossible to control, and putting some minimum sound quality requirement on uploads would only end up eliminating a lot of the cool rare / weird stuff that's the draw to youtube in the first place.
it seems like the thing that makes youtube special is exactly what keeps it from matching those specific sonic qualities touted by its rivals.
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