USB-A/B for USB2.0 lacked the pin-count to provide compatibility with other connector standards by using a passive adaptor (except a few like PS/2). It also lacked the data bandwidth to encapsulate many other connector electrical protocols when using an active adapter except a few like RS-232 and 100mbps Ethernet. It also couldn’t deliver much power either - 500mA at 12V is only 2.5W - enough for a mouse or webcam.

True, I just realized that this is for display bandwidth. And also in the future, possibly for inexpensive 40gbps networking/video/gpu

For me the true killer feature of USB-C is charging everything. Finally, a single charger for the laptop, the tablet, the phone, the router etc.

I never saw anyone hooking up a monitor via USB 2.0

I used the usb2.0 to dvi adapter a while back on a an old polycarbonate mac for which I wanted to drive a second monitor.

It actually worked really well for that use case (coding/ web browsing). It probably wouldn't work at all for anything stressful. Getting the driver set up was a little challenging compared to the usual no effort required.

The website for the product... well frankly not good. https://www.newertech.com/products/viddu2dvia.php

I've seen them for sale on Amazon and elsewhere. I always thought they'd be neat to throw in a supplemental kit bag for a second display on the go. I think some of the smaller ones were even bus powered.

I've seen those usb 2.0 display adapters and I never used one but I heard that they had low refresh rates and/or low resolution, due to the 5 volt limits.

I personally use a usb 2.0 NIC so that I can be packet capturing on multiple switch/vlan/ingress or egress at the same time.

Bus powered and decent res (not 4k), but very workable for writing code a casual web browsing. I put a comment about my experience with one above.

Those are USB 3.0-based DisplayLink connectors.

Any supposed USB 2.0-based display connectors (I’ve never seen any, I’m just speculating) would have been some VNC-like contraption involving an emulated frame buffer on the host.

I've used bus-powered USB 2.0 display adapters in the past, even up to 1920x1080. They're usually a software-based renderer writing to a frame buffer on the USB device. Big updates or lots of USB traffic meant dropped/torn frames, and lots of extra CPU power used to drive it. It worked well for word processing and light web usage, but you wouldn't be watching an HD movie on it.

I've seen those usb 2.0 display adapters and I never used one but I heard that they had low refresh rates and/or low resolution, due to the 5 volt limits. I personally use a usb 2.0 NIC so that I can be packet capturing on multiple switch/vlan/ingress or egress at the same time.

They weren't that great but we had them 15 years ago. VTLink. Dual monitors for laptop users, PC or Mac.