At least at our university it is the default browser on every machine. All have ublock origin installed — I wonder how this would affect browser metrics.
I think that's proof more of an idiosyncratic IT department than of Firefox's secret popularity... a single university, or school system even, wouldn't meaningfully affect the statistics.
If anything, Chrome and Safari (or at least their webviews) have a huge edge because of default mobile installations. Gecko will never be 100% compatible with Blink & Webkit, regardless of UA masking.
