Well.... if you think critically about Fury X and its real world OC potential, and how HBM was super stubborn in anything you did with the clocks... And if you also look at how Ryzen behaves nowadays in terms of how it is optimized for a rather tight max clock range...
I find it reasonable to believe that AMD is taking a different route with its newer hardware releases. They push it to the edge themselves. In the case of Fury X > Vega it would make complete sense to do so, not only do they need the performance, but the competitor is essentially doing something similar but calls it GPU Boost 3.0, which essentially only gives you less guarantees on the box (300mhz gaps between stock and actual clocks) but has the same net result - and yes, it uses less power = less heat and therefore still offers OC headroom, but then again, look at the OC left on the 1080ti Lightning - 3% really ain't much is it...
Now that I think of it, RX580 is another great example of AMD eating up the OC headroom and marketing it themselves. Its a real trend. Look at Intel's Kaby Lake and X299 releases: increased TDP for clock bumps out of the box. Its a simple method to hide stagnation.
