VP9 can be hardware accelerated, and AFAIK current Chrome supports hardware acceleration for VP9 with hardware that supports it.
Which means that Google is wasting tons of electricity by pushing their own codec. That's not good for the environment and for global warming. Extremely irresponsible.
I'd be amazed if anything other than Chromebooks and Android had it.
From what I've been able to find:
NVidia Pascal has full hardware decoding for VP9, as does the NVidia GM206.
And Intel's (now shipping, but not in consumer hands yet until probably next month, IIRC) Kaby Lake has full hardware decoding support, too.
(A lot more existing GPUs have hybrid support, but that's still got a CPU cost.)
Well, YouTube alone is something like 1/6 of internet traffic, and probably a sizable amount of the time people spend on the internet.
And everyone besides Google isn't happy with H.264, either. While it's true that Google is the main source of VP9, Netflix 4K is, IIRC, H.265-only (for which hardware acceleration is becoming more common just as it is for VP9).
This is because Google/YouTube is pushing VP9 streams when they detect that you're using Chrome. It saves them few megs on bandwidth (over H.264) but you suffer for it because VP9 is not hardware accelerated so it chews through your CPU and makes your system less responsive. YouTube/Google also doesn't allow you to set your preference for H.264.
It's irresponsible for Google to waste so much electricity for everyone who uses Chrome.