I have a blog - and a facebook account and a g+ account. The blog gets my best content. But it's not easy to integrate a standalone blog into an existing social graph (social buttons notwithstanding).
G+ gets my less well thought out rants - short stuff. It allows me to cheaply signal to like minded people and hopefully establish new readers/relationships. I don't care if I offend people on G+ because I'm there to attract the like minded. So I say what I think.
And facebook is just a socialisation wheel greaser for local friendships. Here I'm much more guarded. I use content posted by people as conversation starters for when I see them in real life. I might have to deal with these people - so I keep it light, fluffy and fun. I personally don't care if facebook deletes all that content. (I see it as a medium risk since facebook isn't a particularly diversified business)
I decided a while ago that I need to engage on all these platforms - because concentrating solely on a blog only increases your overall isolation to your local life - cause it takes an enormous amount of time - and even your closest local friends aren't likely to even read it.
It might mean that I'll never put enough time into the blog for it be a standalone success. But the odds of that ever happening were slim to nil anyway - even if it did get 100 percent of my time. And there would have been a very high chance that I would have been miserable because such dedication would have led to a high degree of isolation.
This is the right balance for me. I don't expect everyone to have the same view - but then I'm not claiming it's right for everyone.