The foundation of the public trust is the appraiser/client relationship. The only reason your work is marketable is the perception that your clients and prospective clients (and their downstream users) have that the results you produce are reasonable for their usage.
Try getting work from a client who's selling their packages from some investor who has blackballed you. It's not going to happen.
These various users, which often go beyond just the client, make their own decisions about how much or how little. Your choice as an appraiser is to either accept the assignment and do what you need to do to make it right, counteroffer to do more if you think what they're asking for is inadequate, or to decline it. "Telling" them what they're allowed to use is not among our options.