IE is popular because it's per-installed with windows & people are lazy.
Chrome is popular because it's pushed on every Google site. Plus everyone wants a bit of that Google magic on their computer to no?
Firefox market share is increasing because it's advertised on.... & pre-installed on....... lol you get the point.
Blaming any feature itself for firefox's decreasing market share is simply just a lazy mental model, mixed with a bit of he-said, she-said & anyone but me is to blame.