These are optional, so it is really nothing that effects the privacy of users who do not chose to use it.

Using Google and Facebook as oauth providers doesn't mean sharing anything important with Google or Facebook other than "This user requested authentication for this client (Alovoa)." I wouldn't use it personally because I minimize my use of these companies as much as possible, but it's probably fine by most people's standards in addition to being convenient. Especially since they presumably already have and use their google/facebook accounts.