I feel that downvotes / dislikes don't contribute in large forum-style communities. The "proper" use of them is very useful, but the "improper" usage of downvotes becomes rampant on larger communities, rather than people expressing "this doesn't contribute" with downvotes they end up using them to express "I don't like you and/or your opinion" which results in high-quality posts and comments getting downvoted into oblivion because they do not conform to what the majority deems correct.

This also can be exasperated in communities that are more taste-based, e.g. a community discussing music rather than a community dealing with more objective knowledge.

I guess this is a really long way of saying that I agree with them disabling them but I do not think "mental health" is the concern, more so that they cannot fulfill their intended purpose in larger communities or taste-based communities.