I think that it is a bit more complex than that. Their original plan was for native[1] gaming on Linux.
When it proved hard to bootstrap that and seeing that the Steam Machine itself they started looking for options. Wine was already pretty good but DX11 support was bad. I do not know if it was serendipity that DXVK started showing promises around they same time they started looking into wine or whether it was the reason for them focusing into wine in the first place.
The rest is history, although the side effect is that it pretty much killed native ports for AAA games on Linux [2].
[1] for some values of native. Many, most, ports are based on internal close source equivalent of wine.
[2] I do not really care about native vs proton, but it would be nice if game companies did officially support proton.
When it proved hard to bootstrap that and seeing that the Steam Machine itself they started looking for options. Wine was already pretty good but DX11 support was bad. I do not know if it was serendipity that DXVK started showing promises around they same time they started looking into wine or whether it was the reason for them focusing into wine in the first place.
The rest is history, although the side effect is that it pretty much killed native ports for AAA games on Linux [2].
[1] for some values of native. Many, most, ports are based on internal close source equivalent of wine.
[2] I do not really care about native vs proton, but it would be nice if game companies did officially support proton.