I disagree as well. I’ve come across a great many posts (including some of my own) where problems were reported that automatically locked after 3 months, having never gotten a single response from anyone. That’s incredibly frustrating, and reflects poorly on Plex.
I made the following statement in another thread:
I think the apparent unevenness of old/unlocked threads is due, at least in part, to threads being present before the switch to Discourse forum software. I think the rule may not be applied to those threads without some admin intervention.
Threads in the Feature Suggestions forum never (automatically) close (although we discovered a bug/exception to that a couple years ago).
I have flagged posts, asking for them to be re-opened, from time to time. But I grumble about Plex’s disregard for adequate support every time.