This basically acts as a waste gate (and is the reason VVTs don't have wastegates) and lets air through the exhaust housing without it having as much affect on the turbing wheel.
This is very good insight, and I won't argue the finer points. You hit it. The vane is the only hardware that approximates the function of a wastegate. The max vane tables are analogous to the wastegate psi setting.
As for for the wastegate delete on VVT's, that is strictly a financial consideration, probably even pushed the advent of the VGT.