Likes are not entirely meaningless; they may have a low signal, but that doesn't mean there is no signal at all in them. I think most negativity surrounding likes comes from their use as statistic on posts. But there is another perspective, which is likes given by a user.

I'm not interested in whether a post has 10 or 1000 likes, but I am interested in going to someones profile and seeing what they liked.

Some people don't like to reply or comment, but do want to share that they liked something.

And even if someone likes everything, that is also a signal - it indicates that this person's likes are worthless.