Besides some data leaks you are right, most of these attacks are DDOSes. However is strange that russian authorities don't have the power or will to mitigate them.
The FSB going out of their way to proactively ensure the site maintains 100% uptime even in the face of a rare, massive, and temporary DDOS campaign is expensive and a waste of resources. If you're going to focus your resources on keeping a website that hardly even matters up 100% of the time, you're going to end up having your IT organization disrupted in a far more meaningful way. The organization as a whole has limited resources and is regularly dealing with defending against the most advanced APT's in the world from infiltrating its network and disrupting its activities. Good stewardship of IT means good prioritization.