Therapists make huge mistakes all the time. They are like walking bags of mistakes. They rarely acknowledge it, but they do make them. And I am not arguing here over whether they can or cannot be hurt should a client say something mean about the therapist to the therapist or attack them otherwise (I mean I do believe they cannot really be hurt, but that is not the point I am making here).

I do not believe a therapist can be hurt over a client's issues or past or what the client explains or reveals or pick your verb, about the client themselves. That belongs only to the client. It cannot contaminate or wound or whatever the therapist. That a client may have the same issue a therapist deals with is not the concern of the client. It is the concern and responsibility of the therapist to either limit their practice to those who do not have the same issues or for the therapist to deal with it. It is not the concern or responsibility of the client to protect, take care of, protect, or worry about the therapist. It is not even possible, in my opinion, for a client to protect or take care of a therapist unless the therapist fails to maintain even the most minimal professional boundaries.