There are sites that commercially distribute DRMed video content; say, Netflix. They have a large audience, and they care, whether me and you like it or not.
Using Netflix as the example, Widevine L1 has very limited support on the desktop, i.e. Microsoft Edge on Windows and Safari on macOS.
All other configurations use L3 which is a shared key, e.g. provided by ChromeCDM as it runs entirely on the CPU - which is why Netflix content also works under Linux, albeit L3 is limited to 720p (or 1080p with browser extensions).
Given Chrome's massive browser market share, I'm not sure whether enabling DRM adds anything meaningful to the fingerprint - i.e. I don't think it's possible to revoke an L3 key without pushing out a new version of the CDM to all users of that browser, as has happened once before with Chrome.
FWIW I've tested Widevine L3 decryption works using a ”headless” docker container running Chrome. The only caveat to add is that Chrome must not be started with --headless, but you don't need a real GPU either, Xvfb works just fine.
I've never used Netflix (or other streaming sites like them) because of the DRM. Youtube manages to prove that a streaming model can be very, very profitable without it at all, as does BBC iPlayer.
AFAICT, the server can avoid serving the DRMed content until the browser proves it has a legitimate DRM-respecting playback capability, which is designed to be hard to feign. That is, unless something like [1] is correctly implemented in the headless mode, DRM content won't be available anyway.
There are sites that commercially distribute DRMed video content; say, Netflix. They have a large audience, and they care, whether me and you like it or not.