Github issue system is lacking many features that Mozilla needs to track bugs (eg. proper dependencies). It's true that bugzilla is not as welcoming as github,

Github issue system is lacking many features that Mozilla needs to track bugs (eg. proper dependencies). It's true that bugzilla is not as welcoming as github, but things are improving. For instance you can now login using your github account - that removes some friction. And wven if you file your bug in the "general" category of the Firefox product, it should be triaged in a few days at most.