Account trading was not closely monitored prior to the implementation of the merit system. It seems that only account sellers were tagged by the Pharmicst. However, after the introduction of the merit system, account trading became widely tagged.
You got that mostly right.
If you can find someone (like maybe Lauda) who was tagging account buyers/sellers before me, please let me know because I
think I was the first to start doing so in 2016. That's because I got scammed for 0.3
BTC by
TimSweat; he had green trust and I stupidly thought that meant something more than it did. After that, I realized how dangerous it could be if an account with green trust got into a scammer's hands--and back then, there were all sorts of threads in which accounts like that were being sold.
I didn't discriminate when handing out the red trust back then, but as I said there should be room for second chances. Every case is different, but in general account trading is a net negative for the forum. Not everyone thinks traded accounts ought to be tagged, and that's fine. It's good for us to have a wide range of opinions on things, but I'm always going to side with someone who tags an account buyer or seller.
But if it happened years ago? Eh. At this point if the account in question hasn't done any damage and doesn't necessarily have the potential to for the reason I mentioned or because they've turned into a seriously disruptive shitposter/troll, I'd leave it alone.