But goosebook and facegle make backups for their own sake. You're still tied by vendor lock-in and can be locked out of your own data on a whim and prevented from switching to another service provider. They can and do monetize data that users have been locked out of.
I'd rather have my own backup copieS and take my own responsibilities. The scenario you evoke here would not happen if you had proper backup strategy, two is one and one is none.
I'm probably in the minority being so irresponsible with my own backups, but I'm not alone.
Google and Facebook have a lot on the line with regard to user trust of their reliability. Also, they can't monetize data that they've lost.