An alarming number of them have not been through therapy themselves. It is not an across the board requirement at schools and not one at all to get licensed in any state that I know of in the US. Both therapists I pay have made comment that it should be a requirement but that it is not.

I think they can be quite blind to their own cluelessness. Being a therapist is no indicator of personal insight. Of course, I have not had one say anything to me that I did not already know - so I don't think they are necessarily all that insightful or aware of clients either so it does not surprise me when they lack self awareness.
Frankly I would be a lot more surprised if one of them showed signs of cluefullness.

I would not see one who did not admit to having endured therapy themselves. I would not see one who refused to answer the question about whether they had done so or not.

I have enjoyed the movie Clueless several times.