Web developers are, indeed a tiny fraction of the overall userbase for web browsers. Why browser makers might want to cater to their needs anyway is left as an exercise for the reader.
Why browser makers might not want to cater to web developers wanting to use a keyboard on a platform that is used at 99.9% through touch controls, platform on which we both know they neither develop on (when is the last time you made a website on your tablet?) or even test on, is indeed left as an exercise for the reader.
Testing websites on actual mobile devices is generally advisable. Testing them in a niche browser, perhaps not so much, but more people will if that browser makes it easy.
