I think therapists can be helpful assuming you have a goal. I’ve consulted with a few over the years about the main one I had the problem with. I went with the topics of:

“I need to know if my therapist is behaving ethically”

“I need to know if this is a normal therapy reaction from a client. I haven’t been able to get a straight answer from my therapist”

“I need to decide if I want to switch therapists.”

“I need your help to leave a toxic therapy relationship.”

I think if you’re looking to vent or don’t have direction, many therapists wouldn’t want to get involved for fear of disrupting another therapist’s work. However, if they see themselves as helping you towards a larger end goal, they are more willing to assist.