Pam: In the scenario you describe (abandoned plans or "removed" fiduciaries) I agree with you - but with "routine" admin, can you explain why the 3(16) is more efficient than non-fiduciary outsourcing of that stuff? We do distributions (all kinds) mandatory cash-out processing, DRO review and "Q"DRO-ing, loans, and a whole lot of other stuff without being a fiduciary, and without obtain a plan sponsor/fiduciary signature on anything (except the initial authorization to do so) - unless there is an issue. We try (mostly successfully) to not let those mistakes happen that next year will need correcting.
I'm not knocking your business model - but I have yet to see a 3(16) tell me why a "fiduciary" is necessary for the 95% of the stuff we do as a non-fiduciary.