Can you share with us why you want to connect two computers to one display?
Maybe you have two computers and only one display (or only space for one display on the desktop)? Or a games console?
Obviously you can't use both at once, but you can avoid having to dive around the back of the display and re-plug cables every time you switch (unless you really like playing fit-the-trapezoidal-peg-in-the-square hole blindfold).
Or, maybe (like me) you've got two or more displays - in which case one can serve a dual purpose as a secondary display for your main system when you're only using that, or the display for your second computer when needed.
For a long time, I had a Mac Pro 1.1 (and later a Hackintosh) with a coupe of large displays as my 'home' system and a MacBook Pro as a 'work' system that commuted backwards and forwards to the office. When I was doing "day job" work at home I'd use one of the displays hooked up to the MBP. For non-day-job work I'd use the Mac Pro with dual displays.
Currently I've got an iMac and two external 'secondary' displays, normally with an extended desktop across all 3, but each external display also has various other cables plugged in to accommodate a home server (only needs a display when I'm configuring or troubleshooting it), a former Hackintosh now running Linux, my old MacBook Pro and a couple of Raspberry Pis that I sometimes mess around with.
My mouse can be paired with 3 computers, and switch between them at the touch of a button.
I've also got a wireless keyboard which can be paired with 3 systems and switch at the touch of button, that I can use if I'm 'multi machining'. Or, with 2-3 displays and 2-3 computers in play, there's a great bit of cross-platform software called "Synergy" that lets you share a keyboard and mouse between all 3.