There are no arguments against buttons because such arguments are not necessary until buttons actually get instituted. One could argue that they're unnecessary and don't add value, but that's not an argument, just an observation. I could feel that way while someone else could derive great value and enjoyment from buttons.
One thing buttons do add is that you get a clear idea who's engaging with your posts and how. With buttons, you hardly ever post something that doesn't get at least some button ratings. You might get a bunch of positive or neutral ones that are topical to the post. Even if you get a bunch of cuck, shit, and TLDR ratings, that is information about how people engage with your post that you can then either regard or disregard.
With brofists, you generally don't get them unless people really appreciate your post. Otherwise, if nobody responds with a post of their own, you're basically left clueless as to how many people read your post, how many scrolled past them because it was too long, how many liked it, how many hated it, how many just think you're a retarded cuck regardless of the content of the post, etc. With only brofists, it's arguably a purer experience: the only engagement that you get is the kind that people actually want to put in the effort for, i.e. by responding in writing. Or if they don't want to do that, they can only use the brofist to indicate that they really liked it. Otherwise, anything that's not expressed by writing a post is not worth expressing in the first place, so getting rid of buttons improves the signal-to-noise ratio. I'd say that's the only argument against buttons that doesn't rely on one's own butthurt or potato computers.
