This reflects a fundamental misunderstanding, much like how many think standards groups (e.g. W3C) decide how the browsers works.
(Standards groups can invent the best feature ever for the Web ... and it won't matter in the slightest if browser makers don't adopt it. ALL STANDARDS ARE SET BY BROWSER MAKERS ... the standards bodies are just the mechanism they use to do it.)
Likewise, the browser a web developer user uses is already set for them. EVERY web dev (except those at companies big enough to care about the "long tail" of browsers) uses one browser: the most popular one.
It has nothing to do with politics or being complicit, and everything to do with "You have a job to do, why would you make it take twice as long by testing everything with an unpopular browser, when 99 out of 100 times that testing will find nothing and be a total waste of your time?"