I tried to implement this as an extension a while ago, but ran into the issue of assigning unique IDs to titles. That's actually the first problem to solve.
It wasn't insolvable, but there is more than one way to do it, and then it becomes complex if you want to offer options. Should only the first post have anchored title tags? Should the anchors be prefixed by post ID or not, or be random? How do you scroll into view if you don't know in advance which post an anchor belongs to?
It's also possible to make a table of content without anchored titles (it would scroll but not update the URL). But it requires some kind of internal unique IDs saved on the titles in TextFormatter, or base everything on an index. If not using anchors, it should be possible to implement it fully client-side in javascript.
Also there's Markdown and bbcode and supporting both/a mix requires some considerations as well.
Definitely doable, but not a small task to cover all scenarios.
