Emitter Follower / Common Collector as Negative Feedback Amplifier
With Vin=Vb, Aol=gmRE  (gm: transconductance) and beta=1 your block diagram results in the classical common collector transfer function (output VE)
Acl=VE/Vin=gmRE/(1+gmRE).
The loop gain is Aloop=gmRE