Many songs are sped up, and the discovery that this often has the effect of making them sound better than the original may have created a whole new "genre" of music --- nightcore. I've come across some very pleasing "nightcore'd" songs, and listened to the original, but still think the sped-up and higher-pitched version sounds better. It's an interesting psychological effect.

...and I've also noticed the content ID system still detects them, but they probably remain because the IP holders are content to monetise those videos and reap the profits rather than getting them taken down (and earning nothing.) That turns the question into "is adblocking piracy?" and that's a whole different can of worms...

It still works just fine for the kind of music I listen to, no distortion involved.

"I for one prefer the dmca evasion remix..."