I think they mean "clients expect us to be perfect for them [each individual client]" and they can't be all things to all people. I read a great deal of "my therapist should know me by now," "my therapist knows how I would react," etc. That's pretty common discussion on this forum. The thing is, they aren't going to always read, ahead of time, how a client will possibly react to something, and that is where clients get shaken up because clients expect them to know them internally. But they aren't going to be able to do that with great accuracy because, the reality is we can't predict how we, ourselves, will react to things either.