Games aren't built for API's. They're built from new dev kits and applications, and those are here, have been here, for a while now. You know, engines too - like CryEngine that has been in use for over a decade, showing us 'true next gen' before anyone could run it, and it is only NOW that we start seeing console games catch up to that.
Consoles have had close to metal programming for a long time.
PC's have had massive amounts of processing power (compared to consoles) for a long time
The irony is that PC gaming doesn't NEED DX12 to progress, the consoles need it. VR and mobile need it. Systems with weak, low-power CPU's need it. And on the top end, PC gaming needs it to keep surpassing everything else. I suppose that last little bit is what you're looking for but let's face it, we won't see another Crysis in years.
You know how those high end GPUs are sold today? With inferior technology that really has no merit in real gaming, like VR, like 4K on crappy panels, like HDR with high latencies. These techs are all about moving hardware, not about a great experience, and they're all cash cows right now. None of them are mature.
In the end, the only thing that truly carries a platform and technological progress is an honest investment in stuff we can do with it. That doesn't mean more hardware, it means good, lovingly crafted software. Apple and Blizzard are some of the very few companies that understood this. MS has a love-hate relationship with it. A few smaller game developers also have it.