So you say that you get more actually helpful comments on your blog. But: Do those comments help only you and your blog or do they (possibly transitively) help to improve rationality overall which is the stated goal here?

You don't say it but I wonder whether you propose to or wish for more constructive comments here.

Is that a worthwhile goal here? Maybe not. Gotcha (meant humorously; to point this out as an example of your 'accusation').

Can this be generalized to comment cultures depending on blog topic?

I wonder whether you this kind of comments on your blog.