If spambots are a real concern here I could picture other measures taken. One could trial human checks if under a minimum rep score/game library purchase level to necro (or exclude them altogether using thresholds if it was a big enough problem).

While for the latter downside you bring up it could perhaps be addressed by implementing an auto lock for release-only news topics. I've seen enough useful necros in online forums either by the OP or others that auto locking for all topics seems a rather heavy-handed approach but granted I'm not as familiar with the boards here.

I know Reddit now uses auto locks for other reasons such as to prevent later vote brigading and also it's in their commercial interest to force new content creation but it's a prime example of an abundance of redundant and continually re-hashed topics (though it's not like one can bump old topics to gain eyeballs so the system isn't exactly comparable).

That said it's not like I'd lose sleep over it if it were implemented here just rather I'm always surprised there are those who'll add to thread bumps just to complain of necros without a real need to that I've seen (at least your contributions added something of substance :)). Enough of my wild digression though.

OT: I still use IRC regularly but primarily for tech chat and getting in touch with developers, apart from that many more mainstream communities have moved to newer platforms. If IRC v3's persistent server-side chat history was more widely implemented I could see it making more of a comeback tbh.