Okay, so, youtube targets a small subset of users, and changes their experience capriciously, and to suit their own purposes.

Firefox, it turns out, has a built-in telemetry system that defaults to enable exactly the same behavior: changing your system, to suit their desires.

You’re words “a big evil conspiracy to use this mechanism to uninstall Internet Explorer from peoples' computer” are misleading. No one would propose that the intent is an attack on Microsoft applications. Rather, the intent is to blindfold users on a whim, should a Firefox component prove inconvenient to the providers of Firefox. Ostensibly, in the event that some add-on or extension threatens the bottom line for major backers of Firefox’s funding.