Downvotes seem to only spread negativity and discourage contribution. as others have said, you can just report posts if they’re breaking the rules, so I don’t really get the point of downvotes anyway. Better posts will rise above it even when downvotes are disabled.
That was a crucially different situation. On Youtube, users didn’t control communities or make the rules, so disliking, even though it had many issues, was the only way to discourage bad content. Things are different here. Individual users have much more control so downvotes aren’t needed like they were on Youtube. You don’t lose much except the downsides.