This comment in the other sites thread makes the most sense to me.
"Teflon tape is not meant to be used with compressed gas. The theory is that small pieces can break free (and DO while tightening the threaded fitting) and become lodged in the regulator. There are specific plastic rings that are meant to be seated in the female portion of the regulator, and then the regulator is tightened with a correct-sized spanner. The plastic ring allows you to tighten the fitting down properly, and upon compression, provides a leak-free seal."
It's still a bit of a reach but I do agree with the general logic of it. The seal should be created by the plastic washer (or the rubber one built into the regulator) so no tape should be needed on the tank threads.
Teflon tape is your saving grace on the manifold connections. I would not want to use pipe goop on connections to my kegs.