If you do a Google search for text edited or removed from a post, you get the "revisions" page that shows the edit history. Isn't there a way to discourage or prevent Google from indexing these pages?
Only latest, complete version of posts should reflect the actual content of the site. The revision history is just administrative overhead.
Technology changes, information becomes obsolete, and code becomes deprecated. Hopefully, the archive of Stack Overflow will continue to be updated, augmented, and incorrect information removed.
As a matter of prestige, Stack Overflow should not accumulate endless search hits to information that has been explicitly removed or corrected. There is also the illegal information (Links to pirated material in the edit history) that will be hosted on Stack Overflow forever.