Sounds like there's two separate questions here:

1) did your therapy experiences involve competent, ethical therapists?

2) can therapy be helpful?

I think an unskilled or unethical therapist can do tremendous damage. An unskilled civil engineer can build a structurally unsound bridge that collapses and kills lots of people. But you wouldn't conclude from that the problem is civil engineering, right?

Therapy can be very helpful if you have a good therapist who is a good match for you and you're not being sent there to solve someone else's problem (like your parents) but rather go of your own accord for your own reasons.