Because all three are APIs which try to provide a lot more control over the GPU to game developers. And I wouldn't know of any other similarities that DX12 and Metal share...
Yes for the XBox ONE, although there are some small differences with the desktop version, at least until the upcoming Aniversary update.
But the point he was making was that there is no need for DX12 because Vulkan works everywhere else.
Right now Vulkan is only supported on custom Android 6 forks for Samsung S7 and NVidia Shield, Android 7, GNU/Linux and Windows on a restricted set of graphic cards.
Hardly a market to target for game developers that want to reach as much eyes as possible.
Windows 10 users are already 45%, with around 41% having DX 12 GPUs + plus around 20 million Xbox One units.
As for market size of Vulkan, some S7 and NVidia shield as part of 10% Android 6, 0% on Android 7 until it reaches stable and of course those other 55% users that might have a Vulkan compatible card.
You didn't answer the question. DX12 has less market than Vulkan, and will always be limited to MS systems. It's not available on PS or iOS and such. So bringing them as a reason to use DX12 instead of Vulkan was pointless.
> I very much doubt Microsoft will bother to support Vulkan if AAA studios don't ask for it.
They will eventually, when they'll get fed up with MS lock-in stupidity. In order for it to happen, competing market should put more pressure on MS. MS drops lock-in only from fear of competition. And it will eventually happen - there is no need for reinventing the wheel.
People in the industry call that support and productivity thanks to proper tooling instead of leaving each one alone to scatter around for half baked FOSS libraries, but I don't expect activists without experience in the big boys league to understand it.
> People in the industry call that support and productivity
People call that MS tax, since it makes their development more costly. Whether it's developers who work on their own engines, or engine developers who provide their engines for others, this cost is passed to the end user in the form of more bugs, slower development and so on. No sane developer appreciates lock-in. But currently they have no choice.
What people? Indies and FOSS activists that probably still write M$ to this day and believe that Sony and Nintendo or even Sega in its former days are any different.
I really bet none of those ever walked the floors of GDC.