It depends. Hicksian
Keynesiansism, after WWII mostly popularized by Samuelson's famous textbook and nowadays via Krugman's blog, does indeed treat recessions as deviations.
Post Keynesians like Minsky
or Paul Davidson do on the other hand focus on disequilibrium tendencies, i.e. a financial crisis like the current one is not an anomaly but a regularity (and historically this is of course right).
As Keynesianism is about economics it doesn't assume the development of nations. No idea where you got that form.
Of course you are totally right that no Keynesian is anti-capitalist. Keynes wanted to fix the problems of capitalism, not throw it overboard. And given that demand management worked so well after WWII I fail to see why we should throw it overboard.
But let's also focus on commonalities between radical lefties and social democrats. If you want to read something from a guy who also thought about the business cycle at the same time as Keynes and came up with similar ideas yet unlike Keynes has a socialist and not a liberal political background I suggest this brilliant article
by Kalecki. He predicted in the fourties that the political power of capital will undo any attempts to create full employment via demand management and his prediction turned out to be right.