Possibly socialogically, it is interesting to me that I totally don't mind scrolling up to the top on my phone, but it bothers me on the computer
Nah, it's not you, UX (user experience) design. You actually nailed it earlier - the flick to the top with a thumb has an accelerating effect to it that means you can move up quite rapidly to the top of a long scrolling document - this feeling was originally perfected with the iPod scroll wheels I think, but has really gotten nice on modern flat glass devices. Mouse movement, even with a wheel, is generally capped so that the maximum vertical speed is less. Especially if you are like me and have lots of post per page (I do 50), it takes longer and more physical effort to get to he top. Plus, your habits probably mean that as you read, your cursor slowly migrates toward the bottom of the screen, so even if the scroll is fast you still have to move your mouse all the way from the bottom to the top of the screen which, again, physical movement. A track pad on a laptop will make both of these even worse.
If you have a high-end business or gaming mouse designed with this in mind (like the Logitech Master MX I used to have), you can make quick mouse movement and scrolling more possible, but for most users the touchscreen will be a faster, more comfortable device for quickly scrolling all the way to the top.
We will get you a bottom link eventually.