End users don't care about the management of firefox being messy or not. They install the web browsers that are advertised at them. Every time they go to a youtube link or to their gmail inbox there is a banner ad to install google chrome. Corporate IT now installs google chrome by default on work hardware at a lot of organizations because it works out of the box with their google business products, so you are familiar with google chrome from the workplace or even in schools with chromebooks now too. Google has millions of dollars more to blow than Mozilla at this sort of arms race and its shown in the market share.