The march of progress, maybe?
Are you still watching TV over-the-air much, or maybe via cable, or better still, IPTV (streaming)? Do you still use a home dialup phone, or, most likely, a smartphone… which is a pocket computer, not even a real phone?
USB 1.1 was replaced by USB 2.0. The way that the USB specs were written, however, any device could all-of-a-sudden be called USB 2.0. Technically speaking, a USB 1.1 device — usually a mouse, a keyboard, a graphics tablet, some human interface device that’s not so fast — runs at 1.5Mb/s (low speedc) or 12Mb/s (full speed). By today’s standards, not so far, eh?
But a bunch of these… AT Keyboard, PS/2, Parallel, Modem, Mac serial, Centronics, Serial/COM (DB-25, DB-9), etc. were going at kilobaud speeds. Each one was different, too. What USB did was replace a big pile of different interface connectors with a single connector.
USB 2.0 was introduced to continue that trend. It added a new 480Mb/s (“high speed”) mode, but kept the other two slower modes. This new spec now covered the functions of Optical TOSLink, some uses of Firewire, ADB, audio (digital), AAUI/Ethernet, SCSI, etc.
Now, of course, mundanes buying computer systems don’t know all this. They know USB 2.0 is the New Hotness, so they don’t buy USB 1.1. The will wind up buying totally USB 1.1 compliant hardware, but overnight, it’s all called USB 2.0 now.
USB3 is a similar thing… it added 5Gb/s and later 10Gb/s connections. But it included USB 2.0… in fact, every USB3 connector mandates normal everyday USB 2.0 on two connector pins. If you look at the chart, USB3 was a full enough replacement for eSATA and made a better SCSI and networking replacement, but most of the promise was “things that are yet to be.” And as with USB 2.0, any USB thing can be called USB3, even if it’s not really able to support higher speed modes.
In time, USB3 introduced a technology that lets other things run over the same connector, so at some point, some USB3 ports allowed digital video options that replace DVI, VGA/SVGA, HDMI, etc. In fact, the reason it doesn’t replace DisplayPort is that USB3 can offer DisplayPort over a USB Type-C cable.
And now USB4 incorporated most of what Intel created with Thunderbolt 3/4, faster sill and still doing DisplayPort for video. The difference is that Thunderbolt is certified under both USB and Thunderbolt rules, which mandate each port does practically everything, and USB4, which lets a mouse be USB4 if the marketing folks want to dub it that.
