I experimented with screens volcarona two years ago and at that time everyone seemed to think screens fire wasn't legit at all, but then again when i started using defog charY around the same time people were calling me crazy.
Today screens volcarona is a semi-legit, semi-meme strat that works OK in LTM and UU tours, but on high ladder having two pokémon 4x weak to rock is purely masochistic, and no amount of torkoal is going to change that.
As you said, it's only "successful mid-ladder", as sample teams usually are. Just wanted to put that out there.