Sure, you shouldn't always get to be root on other people's computers. But you absolutely should get to be root whenever you want on your own computers.

Depends, that is how normies get Ask Jeeves toolbars.

Now the ad- and spyware just come bundled into the OS, so the main difference is that you at least have some ability to mitigate malware with root.

Interesting choice of example, since malicious browser extensions don't require admin rights to get installed.

An example, I could have picked something else, doesn't make less relevant in how normies mishandle their computers, and if being pedantic with this specific example, unless using Firefox, in what concerns Safari and Chrome installing such extensions can be disabled, at least in corporate computers.

No, I think the reason is that not letting user have full control over hardware is more profitable for manufactures, government and economy as a whole.

Anyone that misuses their root account to have an exploit taking place inside the organization gets shown the door.

And what is "getting shown the door" with your own device? A Fullscreen message telling you you are now banned from the device you spent a months wages on?

Ransonware, or a systray full of little applications the nephew has to fix during Christmas vacations.