HTML is a bad choice - I want to be able to reorganize my site without have a million dead links. Even if I know what the correct organization is today, requirements will change and so in the future something will be wrong.
With rST I can link to a section and move that section to a different document and the links all still work (or if they don't I get an error for each and so I know where to look). With markdown and html I link to a specific document and since each is a document generator there is no warning if I typo the page name (there are a number of tools to look for dead links in html). With markdown I cannot link into a section of the page, only the page itself (some extensions to markdown allow this)
What you see as annoying, I see as a strength. You shouldn't break links; they don't only exist in your site. People will have them bookmarked or shared on the web.
There's nothing worse than finding a post online that seems like it will cover your exact issue, but the link is now a 404.
I get what you are saying, but the world is not static. The concept of bookmarks and deep links thus is flawed because they do not/cannot follow changes in the world. Bookmarks need to take a snapshot of the reachable web (this is probably impossible...) or they need to expire after a few months so that the world can change.
I would hate if all nurses manuals had to accept the bookmarks of some book from 1820 just because someone once had a bookmark to the bloodletting section.
With rST I can link to a section and move that section to a different document and the links all still work (or if they don't I get an error for each and so I know where to look). With markdown and html I link to a specific document and since each is a document generator there is no warning if I typo the page name (there are a number of tools to look for dead links in html). With markdown I cannot link into a section of the page, only the page itself (some extensions to markdown allow this)