Background:

Initially raised as a discussion on enwiki.

Feature summary:

I'd like to be able to filter page history page per section so as we can see only the changes that have happened to specific sections from their creation to their current state or their deletion (if they don't exist anymore).

Inside the original discussion there are some crude examples of how this can be achieved.

Use cases and benefits

Useful on articles to see how certain concepts (usually equivalent to sections) have evolved over time and when certain characteristics have been introduced and why. This becomes especially needed on topics which have disputes going on on their talk pages.

Long discussions can benefit as well for the same reasons.