Pinning threads

On many forums, there is the ability for mods to pin or sticky a great discussion. I can immediately see a couple examples where this could be useful.
1. There are a lot of "how do I get better at chess?" threads.
2. There are a lot of "why did I get banned?" threads.

It's a bit frustrating to see where the community puts in a lot of effort in and then the threads end up being ephemeral and a couple days later. This could save people a lot of energy and just say "read the sticky" instead.

I appreciate your thoughts and ideas, but I think this is just not practical. Not only would this be a bunch of extra work for the mods to select threads, the question is also if a "higher instance" should chose what the users see in first place, instead of it being dependent on where the last message was written (as it is right now). Another question would be which criteria make a thread pin-worthy and I guess that's not generally decidable.