Specs take a long time to arrive. There's a lot of toing and froing, discussions and revisions. Many take years, some take decades.

Netscape, Google, Microsoft and Apple have all been guilty of losing patience and ploughing ahead by adding features to their browsers that aren't fully standards-backed at one point or another, but it's usually the decisions of the market leader that have the biggest impact. Lots of people develop for Chrome and assume it'll work elsewhere as a result, or worse they don't care.

"Guilty of losing patience" is nonsense. If you look at the process by which web standards advance, it requires that two or more vendors have created proof-of-concept implementations, before the standard can be standardized. That, in fact, how standards have always worked.

As a Firefox user, I don't like the results either. But I don't think any of the actors in question are acting in bad faith. Not even the lazy web developers who build Chrome-only games; why should they build shit for me, if they don't want to?

I'm a web game builder and I'm definitely guilty of that. However, I make the games for myself. If other people want to play, fine, but I have no personal reasons to support anything other than my own setup. I presume a lot of other indie game developers are the same. I don't make any money on the games and have neither time, resources nor interest in making it compatible for browsers I don't use.

Yeah, this is pretty much it. I definitely have tried with a lot of browsers, I learnt about a lot of quirks of different browsers doing this project. I just gave up on Firefox because I ran out of ideas to try. It wasn't due to lack of trying.

Anyway, someone made a suggestion of what to try in another comment, and turns out it was really easy, so now it's fixed. Firefox just does software blurring which is super slow and so I just had to turn that off entirely for Firefox. So Firefox performance is now okay enough, although still not quite like Chrome.

For example Chrome has implemented Web Components which Polymer uses. Most Google sites (e.g. Google Play Music) use Polymer, so they work fine and speedily on Chrome, but on other browsers they use a slow Javascript polyfill.

Actually I think Firefox supports them natively now but until very recently it didn't.

car analogy. imagine one car maker sells 80% of the cars. tomorrow they change how the gas pump works to only fuel their cars, but it fills a tank 5s faster! and they use the fact that they got 80% of the market already to force all gas stations to change to their pumps or lose their customers. now everyone buys their car because they can't even find a gas station with the universal pump anymore.

companies that move "faster than the standards" always do so under the guise of offering better products faster, but with the actual goal of locking in consumers to later enjoy a monopoly. see sony trying to always come up with a new media device, minidisc, memorystick, etc.