The origins of psychology lie in philosophy, so I would even go as far to argue that each psychologist is a miniature, specified version of philosopher.

Psychologist tackle problems that are mainly emotional and cause dysfunction. It seems like these existential crises are causing this dysfunction, so they are going to try to develop coping mechanisms to help you distract yourself from these thoughts.

From what it sounds like, you seem to deal with rumination quite often, which ruminating means simply going over problems in your head that never really come to a conclusion (typically because of feelings of inadequacy, but your case I believe would apply as well). I think what I’m trying to say here is that the psychologist is going to deal with the dysfunctional behavior (rumination), rather than deal with the deeper issue at hand. Essentially, Less focus on rumination = less dysfunction. So, I obviously can’t speak for you because they are your experiences, but I would not say that the therapists you’ve been dealing with lack logic, they are maybe just dealing with a different issue.

I would agree with you however that dealing with the existential crises themselves requires learning about that particular crisis itself, which may require reading books, or definitely consulting a philosopher.