I had a Wacom tablet that comes with one of these. The tablet's only input is USB Type C that requires the other side to support the Displayport alternate mode

I had a Wacom tablet that comes with one of these. The tablet's only input is USB Type C that requires the other side to support the Displayport alternate mode... and computers didn't really have that kind of port when Wacom released it. So it same with a box that has a USB type A port, a mini Displayport, and a USB Type C port. You can then use an A-A cable to plug into your computer (along with the Displayport for video), and then connect via Type C to the actual tablet. In theory, you can also connect the box to the tablet via Type C, and it becomes an extra USB port. It is janky and every time I go through my cables I say to myself "why on Earth does this abomination exist", but I suppose they had a good reason. Now that graphics cards have Type C ports for VR (apparently), it's not a problem. But it was back when they first came out. They ended up having to use a stupid special cable because they made their device too nice (if you did have a Type C port with video out on your computer, you could still use the converter that you paid for). I suppose there is some precedent for USB devices that can switch over to being the host. I remember buying a "USB on the go" adaptor and plugging a mouse into my Nexus back in the day. It worked! A cursor appeared and you could move it around. (Unfortunately, I hated that tablet. My Surface Pro was much better, and it wasn't even designed for drawing. I gave both devices away and now just use my iPad, which still isn't as good as the Surface Pro 4.)