I could see how for some ppl therapy RS could grow into some other kind of RS- though it wouldn't work for me.

However, I think being in therapy and consecutively being friends can't be healthy.
Like come on, could any of us imagine our real friend to be in our Ts role? For one hour (more or less) a week you would meet your friend in some special setting and do therapy then stop and go have a drink with some other friends?
That just cannot work- these types of RS are too different. You'd end up either not being friends or not doing a real therapy. Yes, some friendship can work therapeutically but I think it's important that they are reciprocal which client/T RS isn't (shouldn't be).
Plus paying my friend for his/her time would feel awful (not to mention him/her giving me a sliding scale )