I have an email address for comments at the bottom of my blog posts. If they can write me an email and it's something that contributes to the discussion, I'll include it in a comments section at the bottom of the post. For bigger discussions, cross-post to social is the way to go.
That's exactly how periodicals worked for a hundred years. A letter to the editor that is published in the next edition. That's how I always mentally viewed blogs and expected most niche sites to eventually do that. In fact, a local "neat things" blog was successfully doing that for quite a while.
