Sometimes comments are just comments. If you need a link to figure out whether to take a person seriously (i.e. their comment has no merit free-standing - I'm not sure this is true), a link to a blog ought to be sufficient.

I know I frequently click on the links people provide when they make blog comments, but I don't think I've ever looked at someone's Disqus history. Disqus cuts across multiple sites in potentially drastically different arenas; it's too horizontal. But when someone provides a link, they usually mean it to be relevant.