+1 for locking over hiding bad threads.
A locked thread can be used as an example. When future bad threads pop up, one can link to the old bad thread and say: "This new thread is very similar to the old bad thread. You can see why the old one was locked, and there's no use in rehashing that. Therefore I'm locking this new thread"
As it stands, because the old thread is hidden, the community collectively has to rehash the issues here. Its a duplication of effort both for community members and the moderators, and could erode some trust from forum regulars that notice such quiet removals.
Maybe I'd think about old bad threads like old bad code? Old bad code (usually?) doesn't get deleted on Github, it just gets marked as old and bad and everyone can use that as a reference point / lesson to improve the project gong forward. I'd argue its a similar story here in the forums.
Regardless, thank you to @matchboxbananasynergy for doing the hard work of moderation for a great project. There's always room for improvement, but I still find these forums to be miles above and ahead of what I typically find elsewhere.