Interesting. This is not a feature I would have ever considered. In fact, I am always frustrated when a site I am linking to does not give me more granular anchors to link to. I'm tempted to reject this for that pet-peeve alone, but recognize that there could be other factors. A stronger objection might be to avoid feature creep. So, can you make a case for why this should be included?

Assuming this does get accepted, another concern is the name of the option. "Max" seems illogical from a certain perspective. In fact, the proposed docs state "highest heading level (deepest <hN>)." 'Highest' and 'deepest' are opposites. I understand how we got here, but we need to account for document authors who don't understand HTML. And then there is the fact that the name does not connect it to anchorlinks specifically. I don't have any better names to propose, but want to make sure some thought was given to it at a minimum.