> One challenge not discussed here is when an accepted and highly voted answer _used_ to be a good answer, but no longer is in later versions of whatever software/platform/library is discussed. This is also something that gets worse over time, like the uniqueness problem.

It's not discussed because the solution is kinda obvious.. wikis mean editing, right? Even by anonymous users? That's also how it works on Stack Overflow. Edit the answer to make it better, more up to date, or add a disclaimer at the top that it only applies to very specific versions as needed.