Part of the reason h.264 was such a big percentage of video was that they messed up the licencing of the follow up so badly which was supposed to supplant it.

Not that the licencing of h.264 wasn't a mess too. You suggest it was free for web use but they originally only promised not to charge for free streaming up until 2015 and reserved the right to do so once it was embedded in the web. Pressure from Google/Xiph/etc's WebM project forced them to promise not to enforce it after that point either.

https://www.wired.com/2010/08/mpeg-la-extends-web-video-lice...

Cisco paid for a binary version of a decoder that could be downloaded by Firefox as a plugin. They could only do so because of a loophole around a cap in fees that they were already hitting so it wouldn't cost them more to supply to every Firefox user.

Yes, but what are we arguing about here really? I've never said monopolies are good or that MPEG having competition was bad, just that MPEG did a decent job of developing widely used standards at the time and the (still patented) web codecs came decades later, funded by monopoly profits. The alternative to MPEG's pooling and standards wasn't AV1 in 1990, it was RealVideo, Apple Video, Sorensen Spark and quite possibly single vendor lockin for all digital video, as happened with operating systems.