I'm not at all happy about those things, but this is an issue of tradeoffs - the blog I'm talking about isn't my key business, it's merely a side thing for occasional announcements. My key software project is SQLAlchemy, I run my own Trac instance, and I regularly have to babysit it for when it is getting spammed or crawled or slowing down my server or whatever - but I want to own that data and not give it for free to github, so I make the effort. Similarly, I run my own Jenkins servers instead of relying on Travis and I host them on my own EC2 instances. Services and data which are important to me I self-host. Blog comments for me are not.
If I were running a political blog where I'd like to invite lively discussion from a wide variety of individuals, then I'd probably want to take the effort to self-host. But as we all know, if my political blog is visited by folks the US government wants to know about, I will be coerced into secretly sending all my data to the NSA in any case.
> just for your laziness to maintain a blog software (which _really_ is not that hard).
Of course it's not that hard - but when you say something is "really not that hard", you have to consider that as an OSS developer, I am babysitting literally dozens of technical streams, including services and hosting for my projects and technical issues for all kinds of people every single day, all of which is effort I put out for free, save for whatever I get on gittip. Every new service or software I have to host and babysit adds to what is already a formidable amount of plates to keep spinning - so those things that I do self-host have to be worth it. I write only a handful of blog posts a year which are themselves of little consequence and entirely technical. Nobody needs to comment on them and the people who do are certainly technical.
The existing solution, WordPress, is far too difficult to maintain, and it is some of the worst written software in history - I wrote about the many issues I had with it here: http://techspot.zzzeek.org/2010/11/21/how-coders-blog/ .
I'm in no way implying that a self-hosted comment server isn't a fantastic idea and something sorely needed - if a non-commercial, privacy-oriented organization wanted to host and maintain it for free use by others, I'd switch from Disqus immediately.