Feature summary: The special page EditPage should have support for jumping to and editing a single section in a page. For example, on English Wikipedia, [[Special:EditPage/Human#History]] should direct the user to https://en.wikipedia.org/w/index.php?title=Human&action=edit§ion=3 (as of the creation of this ticket).
The immediate use case for me is to speedy up opening large pages in Wiktionary, whose section headers are very systematic, as such, section numbers fall out of sync way faster than section names. In an entry, each language is given a level-2 heading with its name. So if one knows an entry has a given language, they should be able to easily and directly edit it, without having to load the entire page (which can take a little while for larger pages). Similar arguments could be made for Wikivoyage.
Courtsey subscribing Nemoralis as requested in an informal off-wiki conversation.