Metal, on the Apple platforms, is similar.

More similar to DX12 than it is to Vulkan?

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...

Metal is inferior to Vulkan.

Metal is and will always be exclusive to apple platforms.

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.

Vulkan market is MUCH bigger than DX12 market right now, no matter how you put it. It's like at least 3-4x bigger.

Just think how much more popular Windows 7 is compared to DX12. Xbox One is nothing in comparison.

Have you checked Steam hardware survey lately?

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.

That is not what Steam hardware survey says, given the amount of Windows 10 installations plus XBox.

Which are MS systems. So again, no point to bring Apple and Sony as examples of why DX12 is preferable. It's useless there.