Nowadays, not only do a significant portion of the population not know or care what the difference is, they just use Chrome because "Google" and "the internet" are indistinguishable.
I hear the same is true about Facebook.
Yet both cannot be logically true, and Facebook doesn't make their own browser (though their app does use an embedded version of Chrome).
Imagine seeing "the internet" like a gigantic bubble bath. There's some very large bubbles, like Google, Facebook, and Microsoft till some extend. Many can overlap, touch each other. Some small ones get absorbed in larger ones. Some are more omnipresent than others. But right now, there's still other, smaller ones, and new internet-related startups exist every day (little bubbles). But not all of the small or medium bubbles become large ones.
This might lead to an even more interesting browser UA string in the future.
Like "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36 MOZILLA IS FUCKING WRITTEN AT THE BEGINNING ANYWAY POOR SUCKERS!"
10 years latter, Firefox will take over the world again (when people will have enough of calling Google evil all day without doing anything...), and that part will again be engraved as a useless appendix, with an additional From_Google_The_Previously_Too_Big_To_Care_Much_About_Big_Browsers_Company at the end if you use their browser of that day.
What is sad is corporation doing so much evil they do not even have the time to see the history repeating itself, and the absurdness of their seemingly reasoned development approach (they think...)