Maybe. But if more CFIs had said "sorry, but you need your head in the flying game because you lack the skills and focus to safely operate this faster, more complex Debonair -- and I should NOT be having to do any PIC tasks for you" then perhaps it would have clicked with her that she needs to improve.
Sure, any one CFI might be giving her feedback she doesn't like and she can hire/fire at will, but if you hear it from enough people, you start to take it to heart. In the end if she wants to ignore everyone, sure that's her prerogative.
But a crap instructor can definitely hasten your demise if they don't point out to you "hey, I shouldn't have to get the gear for you... or the flaps... or help you with the A/P... or tell you which runway we need to go to... or point out the airport for you.". But by playing a role in her game of reality-denial where she's doing great in her training and getting ready for her IR checkride, you are providing a totally false sense of security to her in her abilities.
And knowing the student can switch CFIIs willy-nilly b/c she doesn't like you as an instructor doesn't abdicate responsibility of the instructor to give potentially life-saving feedback.