At some point I was considering switching to Disqus for comments, now I am glad I did not. Also, I find it interesting how the explanation sounds defensive (and not clear).
Do not get me wrong though, I think it's completely legitimate to try to monetize the huge community Disqus has built; I just believe there should be a way for website owners to switch to a paid plan and opt out from the ads.
For the last month, in very small numbers, we’ve been testing out a new advertising format: Sponsored Comments. We’re expanding that test based on early, promising results. So soon, it’ll be more likely that you come across a Sponsored Comment.