Yea, no. Apple has nothing to do with this. Especially when they flipflop GPU brands every other generation. As someone who is in this industry, I can tell you Apple systems are in the minority.
That was the whole point of this thread. Since the Mercury Playback Engine came out in Premiere, Adobe's official word has been to go with Nvidia cards because of CUDA performance. When OpenCL support was added a few years later, nothing changed. Adobe people, people in community, professionals all said the same thing. Get cuda. But I guess OpenCL support has dramatically improved since it first came out because there were early tests showing it lagging behind CUDA but I can't find them.
Like I said in my OP, it just seems to be what everyone says when in fact I too would like some hard proof. Linus's video was nice but definitely doesn't give the whole picture. I was hoping someone with a deeper knowledge of the subject could chime in.
As far as spending money on an older card, I don't buy old tech. I'm building a brand system from scratch and tend to make them last 4-5 years minimum. A 1070 would be a little bit more future proof than a RX480 as far as Im concerned. And if I want to game, it'd be nice to play them without compromising.