I think Webmentions could be the solution to the problem: They allow anyone to comment on and add to your writings without requiring to open an account on each and every blog and they endorse elaborate, "readworthy" responses.

Alas, they're used seldom.

Unfortunately, Webmentions are also still a spam vector that needs moderation.

I don't think Webmentions yet are common enough to get much spam, but some of us still remember spam wars in Webmentions predecessors like Pingback.