The link I posted is just a generic bad id link that ends up redirecting to your own Facebook profile if you are currently logged into Facebook. Anyone logged into Facebook will see their own profile.
The link joering2 posted OTOH is actually to my Facebook profile. But:
A) I don't really care (anything I put on my Facebook profile is assumed to be 1000% publically available information anyway).
B) Turnabout is fair play
That said, nice goat!
It may never be clear for each individual feature, but violations compound to form a mess of unpredictability. Facebook generally appears to me as being a company with a very strong engineering culture and so it surprises me a bit that they would let something like this slip. Maybe I'm just not seeing the whole picture and it is a clearly thought-out tradeoff and not simply negligence.