It depends a great deal on context to me too.

My therapist has said I'm beautiful and given other compliments. I've taken them sincerely and never felt they were flirtatious, so much depends on the dynamic, the conversation, the type of therapy, etc.

If my own T told me I was a "catch" or "anyone would be lucky to be with you," I would take it as a kind affirmation and a sign of her esteem, that she has a good opinion of me and wants me to have one of myself too. I consider that sometimes language is literal, and sometimes it is not.

Conversely, I can see the points of those who see it as more unprofessional and hyperbolic too- because therapy and therapeutic alliances and circumstances can vary so much. Each client/therapist partnership is a little different, so the even the same words may sometimes be harmless, helpful, or completely inappropriate all based on the situation.