I don't necessarily agree with this. I think, based on the examples you provide, better advice would be: Don't try to replace a therapist with a life coach.

I think with the right ground rules, there are coaches who are legitimate and can be helpful in certain contexts. I would never go to a male coach, for example (obviously, lol). Before I worked with one, I'd want to know about their training and background, and request testimonials from past clients. I did all that and worked with a career-focused life coach during a job transition that left me feeling a bit aimless. I wasn't seeking therapy. I wasn't unpacking any trauma. I was just navigating a tricky change in life and felt like I needed a little support from someone with more experience than me. It was great. I loved my coach, and she was incredibly helpful during that time.

I think in a context like mine, a therapist could also have been appropriate. But for me, career coaching was a more accessible and affordable option at the time. I think it's sort of like how all rectangles are squares but not all squares are rectangles — a therapist could do anything a life coach could, but a life coach won't be able to do everything a therapist can do.

Of course, I fully agree with everything OP says about carefully vetting/checking credentials before you put yourself into a vulnerable position with *anyone.*