[greeniskool]

It's trivial to bypass that check using a Steam "emulator"

[pxc]

That's not the same as not having DRM

[fomine3]

It's like a game only runs on Windows, but also run on Wine

[Libcat99]

There also often software to strip the drm out of direct purchase games.

The existence of drm removal tools does not make a product drm free, in the same way ms office isn't open source if you steal the source code.