You can use Facebook to log in to a lot of services as well, but that's not really "using" Facebook because you're not doing anything with what Facebook offers. You're just telling a website that you are who you say you are.
Sounds like you're using Facebook for exactly it's intended purpose: to allow someone to build a big database of things that you do to target advertising. You're not just telling a website something, you're telling Facebook what other sites you visit and care enough about to log in to and what your identity on those sites is.
OwnCloud is open source and does the same things as Dropbox (although in really crappy PHP on the server, so you'd better have a lot of spare cycles to burn - it's the first time for several years I've seen file transfers across the Internet be CPU limited).
The problem is that they're comparing apples to oranges. Of course a direct local connection will be faster than two devices sharing the same Internet connection and going via a server, but most of the time that I want to use a server as part of a sync workflow it's because the devices aren't together and I want to do it asynchronously. The equivalent for BitTorrent Sync would involve having a central server somewhere (possibly in your own home) that's always on and is a party in the sync.
Microsoft poisoned them killing the company
Bullshit. Nokia mismanaged itself to death by promoting infighting and sabotaging other product groups (rather than competing with other companies) until adopting Windows Phone and killing internal OS development was the least bad option.