Because it's so easy to fact-check nowadays.
The Krym annexation, unrest at Maidan in Ukraine, conflict in Donetsk, coup in Turkey - this is happening less than 2000km from me. And I have hard time doing any fact checking.
There are conspiracies and propaganda everywhere. Infiltrated social networks, state sponsored shills, ... It is easy to pick sides. But really doing fact checking is difficult.
How do you know whether this image of the BUK system in Donetsk is true? You would have to be familiar with the location to recognize the aerial view. You would have to be aerial reconnaissance expert to identify the vehicle. You would have to have access to the history of movements of the military personnel in the area. And of course you would have to be able to check that the image was not doctored. Or you could stand on that street next to the vehicle when the picture is taken. That allows you to check facts, but then you have to convince others. Your close friends may trust you, but with each degree of separation the trust gets weaker.
Sometimes I think about what I would do to convince the world, that something that I saw is true. Something like cryptographic photo authentication might help - but we had a discussion about that before and it does not work.