I think you are still missing the complete context of the original comment. Once a browser is set as default, for a significant portion of people that won't change unless they are somehow prompted or forced to change it again at a later date. To many people, the browser is just another part of the OS that allows viewing webpages, and they just call it "The internet".

It seems if they were that clueless, they would have had many more opportunities to change default browsers without realizing it.

What other browsers auto-install from other software and automatically change your default?

Chrome?

From what? It automatically sets itself as default?

Yup. Chrome is offered as opt-out bundleware with quite a few Windows apps and Google pays the publishers for this. This is how quite a few regular users switched to Chrome. Even just updating Java in Windows it'll try and sneak a copy of Chrome in with the update.

lets be honest. flash or java plus the ask toolbar have been installed by now, and managed to install chrome.

chrome has a way of installing itself.