The web has definitely had a problem with legacy restrictions driving thinking. We lost nearly a decade with Internet Explorer stagnation and I think that caused a lot of people to assume that the odds of something new going mainstream were too low.

Now we're in a very different place where people upgrade software much faster than in the past and that's likely to start showing up in projects like this where it's actually plausible to think of something like Brotli seeing widespread usage within 1-2 years.