Lel, I own a Titan X. Before that, a 970, before that, 3x680's. I have to go back to a 5870 for AMD.
So ah, Try again.
But hey, if you don't believe me, you only need to see the Fury's benchmarks @ 4k. They mostly don't choke.
4GB was never a choke point for a 980 either, but that didn't stop the AMD fans from crying foul about it. Do games suddenly use more texture memory with an NVidia card? What you're saying still doesn't make any sense.
Let me clear it up since you're talking about benchmarks... Why is 4GB enough for a Fury X but not enough for a 980? "because it's HBM" makes no sense. You need what you need.