Consider "Login with UTU"

[databu]

There's the idea that UTU provides its own social login mechanism. The idea is that this would enable UTU to build up its own per-user DB of social relationships, which might be used to provide this data to clients rather than the other way around.

1. What would this entail?
2. Which SM (and other?) platforms could be connected to this, technically and term-wise?
3. Would it actually provide the envisioned benefit?