You do understand that Mastodon is a part of the Fediverse, do you?
Likes are there so that people don’t litter the comment sections with “yeah”, “uh-uh”, “+1”, “cool”, “ok”, etc., or at least do it less. Some platforms, like Misskey even have a little more choice in regards to reactions beside just “likes”. All in all, it’s basically a part of social networking language. You like something - there’s a button for that. You want to say something of substance about it - there are comments/replies. If you agree something so much that you’d sign every word of it - reblog then.
Of course, it all should be optional. If somebody don’t want it, they don’t have to deal with it.
I am well aware of what Likes are for, thank you. I’ve just seen increasing evidence over the past 20 years or so that they create more problems than they solve.
Likes, +1, and so one are the Cancer for Comments in Generall.