Name: Suzanne/Sue Sebastopol, CA (Zone 9a) Sunset Zone 15
It's always been there, funny how you get used to one thing and never notice these handy things right in front of you!
You can also use your keyboard, arrow up or down to speed your way up or down instead of scrolling.
Lynn's got the right idea. I think the Home key is much faster than looking for, finding, and then clicking on a "Back to the top" link. And it works on all pages. Nevertheless we do have it because plenty of people wanted it.
It took me for ever to remember using the Home and End keys. I am pretty comfortably with them now. No need to learn something else to take their place.