I remember when YouTube comments still had a neat and convenient little "translate" feature. Made it actually possible to practically cross the language barriers in comment discussions.
That lead to many interesting insights and discussions, and then, it was suddenly just gone. Which in practice meant that a whole bunch of people that used to be able to communicate with each other, crossing language barriers (How wonderful!), now suddenly couldn't anymore..
It's like the exact opposite to what the web was supposed to do, and the trend has been steadily keeping up. Removing the downvotes is also removing a form of signaling, and thus communication.
And the trend is not just reserved to YouTube, it's even more and more of a thing in places where it absolutely doesn't belong; Many modern video games do not have an "all talk" function anymore, out of fear nasty things might be written and then read by too many people, possibly leading to controversy in the bored "gaming press".
At this rate I wouldn't be surprised to even see YouTube comments go away for good.