Plugin which stores versions of connected sites

I think it can be a good idea create plugin that registers changes of every connected site. Similar to git system, but much simpler, without branching, merging, etc. So, even if something was deleted or changed on some site, connected users (with such plugin enabled) will not destroy this data, but add a record to their tracking file. So they can browse the site at every moment in the past, as you can do in Wikipedia articles.
What do you think about it?

The issue proposes a plugin for recording changes to connected sites and browsing historical versions, but names no files, tests, or entry points. Start by locating the project's plugin and site-storage architecture, then determine the data model and integration points needed for version history. Done would mean an agreed scope and design for preserving and viewing past site states.

Written by the indexing model from the issue text.