Likes are useful tool as they provide great means to express encouragement or just thanking the author for their post/comment. They reduce visual clutter and if someone doesn’t want to use them they are not something obligatory.
Yes, sometimes they can be corrosive. E.g. if heated debate happens and a lot of people watch it, sometimes likes have cumulative effect - when you see someone’s comment which already has a lot of likes it causes positive bias to some degree. Likes attract more likes. So likes on comments can encourage populist behavior. This gets especially bad when there are both upvotes and downvotes and/or some filtering algorithm (show “best” comments, hide “bad” comments) but it happens with just likes too to some degree.
However I don’t believe this is good enough reason to outweigh usefulness of likes. Everything can be misused.