The double click is mainly used because some people didn't like how icons were selected, or "highlighted" automatically. So, a click was used instead of the automatic feature. Thus, what once required one click, now requires two clicks in succession.
Secondly, no, I right-clicked icons on my desktop, and all I saw was a pop-up menu.
Thirdly, you can set you computer to use the automatic feature. It's in "Folder Options".
Why double-click?
A fair while back I accidentally found that instead of double-clicking I could simply right click and never somehow miss having clicked quickly enough, or whatever.
I have never double- clicked since, so what is the point of it and why do so many instructions say "double-click on"?
For anyone who wants to try, just right click on any desktop icon where you normally double-click.

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