"If the ability for Wikipedia to have a neutral article on a topic hinges on the existence of a single irreplaceable person"
i don't think that's been said.
"the right solution is to not have an article on the topic."
false. or i guess we'll exclude most of quantum mechanics and dozens of other things few people are knowledgeable about.
"for a topic area that someone out there cares enough to brigade in the fashion you describe, there surely must also exist a non-obsessive set of users capable of moderating the page without making hundreds of edits per person to it."
maybe, but it doesn't mean they're doing it. as you say, they're non-obsessive.