I can see the argument in favour of classic forums. Keeping everything chronological can help for certain kinds of discussion, and it's easier to sort content by subforums in a way that doesn't scale well with Lemmy. You'd need to create a lot of different communities to keep it all separated, which is messy.

The biggest thing forums lack is multi-threaded discussions. That said, simple chronological helps people at the bottom of the thread get assistance since it doesn't disappear into the web of conversation, so this might also be an advantage of single-threaded forums.

Also, voting gamifies the whole experience, so people are reluctant to post in older threads since they won't get "points".

Finally, threads on Lemmy also don't get bumped, so old content effectively dies. This sucks for troubleshooting since people very frequently have the exact same problem many years apart.

I feel like "release" and "discussion" threads would probably benefit from Lemmy's structure to allow for deeper engagement in sub-conversations, but the core of their use is single-topic requests and, frankly, forums are better at that.