[mining]

Depends how you look at it. Dev time is a finite resource, and spending it on supporting a weird combo of user agent and browser seems likely to lead to less user utility.

[ricardobeat]

Weird combo being Firefox with its default user agent..

[squeaky-clean]

Well, mobile Firefox which is much less common.

[kuschku]

Or Desktop Firefox (~43% of German desktop market) in Google Inbox (during the launch), the new YouTube redesign, Hangouts, Allo, Earth...

Half of Google products either don’t work at all, or far worse, on one of the largest browsers out there.