I switched around 2007 (I think it was Firefox 2 or 3?) because IE didn't have tabs, and then just stuck with it because it was extremely customisable and really fucking good. I never found a reason to switch.
At that time I didn't care much about the privacy/open source aspect of it but in today's world it's definitely a big plus.
The bar is barely 2 years old but IMO has become a great distinguishing characteristic for Pixels already. Also not having a bump makes it an actual feature as phone doesn't go all wibbly wobbly when kept down
Similar reason why people take photos with their phone rather than a point and shoot camera, anyone can do it and it doesn't require extra work to setup.
That's because normal Linux won't be as optimised but unlike Valve they don't want to put actual work into optimising it.