The firefox one is total rubbish. That's like saying that a bike is unusable if you put too many tires on it. The cartoonist is aware that FF comes with NO add-ons at all. Any add-ons are user added.

I have 5 add-ons running, Adblock, Downloadhelper, Xmarks and a couple of others all of which vastly add to FF's usability.

tl;dr The cartoonist has no real idea what he's talking about