Well, VP8 was only released as an open codec in 2010, and subject of patent lawsuits until late 2014.
In 2010 the majority of (YouTube and other) videos were still served as H.264, because no major browser supported it back then and the majority of video playback devices were already smartphones (without vp8 decoding capabilities)
iOS for example didn't support VP8 until iOS12 in 2019, Firefox and MS IE only added it in 2011. Even Google only added VP8 to Chrome in September 2010.
> In 2010... the majority of video playback devices were already smartphones
I find this extremely difficult to believe. In 2010 the only widely used smartphone would have been the iPhone. The Motorola Droid was the first widely marketed Android device in the US and was only launched in late 2009.
The full context, to avoid confusion: "because no major browser supported it back then and the majority of video playback devices were already smartphones (without vp8 decoding capabilities)"
No major browsers didn't support VP8 back then, and among the remaining devices (other appliances than PCs with those Browsers) the majority of video playback devices were already smartphones (not supporting VP8 in 2010).
Wrong. Google aggressively enabled VP8 on YouTube even when there was very little hardware decode. Saved a few megabits per stream on their side, nuked everyone's battery but hey Google didn't give a hoot because that was an externalized cost.
It's why the h264ify extension existed, and forced h264 was for that time a large part of the reason Safari had vastly superior battery life.
You can choose to believe what you want, in reality Google decided to nuke people their battery for fringe benefit to themselves. They flipped the switch way ahead of broad hardware decode support.
You need to put your statement in context of the thread you're trying to lecture on.
The context is that in mid-2010 the majority of the codecs used on the web were based on a closed licensing system, which is objectively true based on the provided information.
Your statement that Google enabled and enforced the codec prior to HW-decoding support is not wrong because of that, just your overall attitude on dealing with information is.
Reason: There was also no widespread VP8 HW-decoding support in 2011 and 2012 in most devices. Mobile chipsets vendors (Qualcomm, Samsung, TI,...) only added HW-decoding for VP8 from 2012 premium tier chipsets, so VP8 was SW-decoded on many devices in the market well into ~2014.
But in mid-2010 (!!) there was no Browser able to handle VP8 even in Software, and no meaningful embedded device supported the codec either
Youtube has used vp8 since 2010. Openly licensed video codes were in use through the mid-2010s.