If you're not assuming good faith what are you assuming here? What's my motivation?

"buttressing commentary on someone else's blog post"

That's how link blogs work. I wrote more about my approach to that here: https://simonwillison.net/2024/Dec/22/link-blog/

(And yes, there I go again linking to something I've written from a comment. It's entirely relevant to the point I am making here. That's why I have a blog - so I can put useful information in one place.)

I'll also note that I don't ever share links to my link blog posts on Hacker News myself - I don't think they're the right format for a HN post. I can't help if other people share them here: https://news.ycombinator.com/from?site=simonwillison.net