Reddit or HN are best examples of Brutalism.
1) I have no clue who responded to me
2) I cannot even delete my comments while Paul Graham shouts about privacy from rooftops
HN is not even functional, let alone bruatalist. And the reason is simple- they will be shredded down because they know it's easy to say things than to do things.
I can delete my comments... not sure why you wouldn't be able to.
I think HN is about as perfect a site for its purpose as I can think of. It's fast. It's fast on mobile. It's fast. It has really consistently interesting links. It has informed conversations that don't generally deteriorate into childish flamewars. It's hella fast.
Besides, after an hour or so your comment is definitely already in Google and any HN crawlers, and probably on archive.org shortly after that.
You're arguing that because it is simply designed it's not brutalist? The whole definition of brutalism is minimal distraction/complexity.
The least brutalist thing you could do would be notifications popping up in the lower right every time somebody responds to you, with a picture, their karma, etc.
Deleting comments again, would be anti-brutalist.
Aside - When I think of the most successful public forum for non-stupid discussion on the internet I think HN (unless you count wikipedia). We should ask ourselves what about this site (or was it the core audience) managed to create the impossible -- intelligent discussions on the internet.