Mainly because of bus architecture. But in some form it exists.
This is what spammed my mind when I started thinking about your post.http://www.linux-usb.org/usbnet/
Interesting problem, one that I hadn't thought of in a while.
There used to be a method to do this through a typical 9-ping serial port, however a special cable was required that crossed certain pins.
This appears to be the best option at the moment: https://www.usbgear.com/link/
OP was talking about USB, and wondering why it isn't being used to connect two PCs. As good as your intentions might have been, your post is absolutely unhelpful.>>1399
It never occured to me that USB is a master-slave thing. I guess the page you linked explains it pretty well>Yes, you may occasionally see "A-to-A" cables for sale; don't waste your money buying them. Those cables are forbidden in USB, since the electrical connections don't make any sense at all. (If you try to use one, you might even short out your USB electronics and so need to buy a new system.) Basically, they're missing the extra electronics shown above, which is necessary to let a USB "master" (host) talk to another one, by making both talk through a USB "slave" (device). (There is one time you may need such cables: when you're working with a hardware development system where the single USB port can be configured - for development only! - in either master or slave roles.)
USB isn't used to connect two computers together because as you said yourself USB isn't designed to do that. I don't see how pointing something that is designed to what the OP wants to do is unhelpful.
Yah OP should have no reason to be fixated on USB and if he is that's kind of dumb.
Shut up glitterboi. I did not know of that technology and it is actually pretty useful to me.
At least his was more helpful than yours lol
magic-wormhole is currently the most convenient & secure way to move a file to another computer(easier than usb).https://github.com/warner/magic-wormhole
I could see the potential it being a module in a bigger system specifically for your case