Probably just knee-jerk downvotes from people who misread the title and assumed you were confused. Honestly, the PS/2 vs PlayStation naming overlap is fair—Sony could’ve picked a more distinct name!
Respectfully, complaining about downvotes is childish (and IIRC against site guidelines). At the point I am reading this, I don't see any indication that (the post you asked about) has been downvoted. Maybe that's because your post influenced others to up-doot it, but I think HN (along with other sites) intentionally fuzz their voting for various reasons.
Moreover, it's just a waste of time to complain about it. Some people aren't going to like the things you say, and it distracts from the topic and introduces noise to try to shine the spotlight on someone disagreeing and philosophizing about their motivations.
Again, I am saying this respectfully and in the interests of how to run an efficient online discussion. I have no horse in the race regarding the PS2 acronym.
I got downvoted too in my original post. I saw it grey, so that means downvotes, but the comment was just saying something trying to help, not even criticizing anything. People that were already young adults (or in their late teens) when the PlayStation 2 came out, and that reads HN today, very possibly know about the IBM PS/2 PC as well.
Anyway, it was just a minor comment, I will stop here
But downvoting because someone added a clarification well, seems childish