Should the answers be edited? Everyones had to work with software on the job that wasn't the latest edition. If we edit answers to software after every update doesn't that just fuck over everyone who's not capable of updating?
As your other responses have stated, editing doesn't necessarily mean "destroy the old and replace it".
A lot of the editing I do is to improve the grammar, reduce fluff, use Rust-standard indentation, improve the formatting, include complete error messages, update links, etc. None of that should affect users of older versions other than to make it easier to get to the core content of the Q/A.
When a new Rust feature comes out, usually the original part of the answer gets a header denoting the compatibility. https://stackoverflow.com/a/28953618/155423 is such an example.
Note that SO does keep a revision log of edits (e.g. https://stackoverflow.com/posts/28953618/revisions) to a post. You can browse that if you think there might be something hidden that's worth exploring. This doesn't necessarily help with search engines, of course.
I often update my answers over time to cover multiple versions, usually as the result of someone leaving a comment pointing out a problem. It's pretty easy to do in a way that preserves the old information (eg. https://stackoverflow.com/a/1576221/8376).
You shouldn't necessarily erase history, but it's pretty easy to move your old text under an Old Answer banner or something, if you still think the info is relevant to someone or even that surfacing the delta between versions is educational.
