- 8.3% average globally doesn't necessarily represent 8.3% of your users or market.
- 8.3% is almost much larger than the metric you actually care about -- the percentage of users that will not use Chrome (or your desired set of supported browsers).
Of course, I used that figure because it’s what the poster used. I looked up what it is for the product I work on and it’s actually only 4% — still an order of magnitude larger than it would need to be to consider not supporting it.
The desired set of supported browsers will always come down to metrics.
That number should grow again. It's becoming increasingly obvious what a privacy leak Chrome is, and Firefox is just as good, making it an obvious choice for anyone who cares about privacy.
Mozilla (Firefox) management thought that installing a Mr Robot advert extension on people's computers, without asking, was a good move, and defended it until the internet outcry got loud enough. With management like that, I find it hard to trust them. Default-installing Pocket was also not entirely defensible and was probably money-driven.
Essentially, both companies have done anti-privacy and untrustworthy actions, and choosing the lesser evil is hardly ideal.
The difference between Mozilla and Google is substantial. Whenever Mozilla gets this wrong it is usually a goof of sorts, when Google gets it wrong it tends to be policy. See 'AMP'.