Today 10 years ago I went to Poland to buy a Phone with pre installed #Firefox OS on. The Phone was a Alcatel One, so very shitty. Two years later I installed Firefox OS on my Nexus 5 instead.
It was a very good concept, but sadly rolled out on too shitty hardware so it never caught on.
Chrome won the browser war because they were lightweight, had better plugins support and it was easy to integrate with you google accounts, which were basically standard.
Firefox at the time was plagued by memory leaks and it was worse with plug-ins installed.
Ironically I switched back to Firefox years ago because Chrome was having those same issues that Firefox was had.