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USB-C hubs and my slow descent into madness - Dennis Schubert
(overengineer.dev)
This is a most excellent place for technology news and articles.
The protocols were way simpler, that's why.
Go read about UART (which you'll find in the Serial connector) which is still used nowadays as one of the standard peripheral inside microcontrollers (including in the cheapest $0.25 ones) and then go read about USB (you can start with USB HID, which is just the stuff for mice, keyboards, joysticks and the like).
Ditto for VGA versus HDMI.
You need a bloody software stack (which in dedicated adaptor chips is transformed by circuit generation software into a in-silico hardware implementation) for the newer stuff whilst the old stuff could often be done with a bunch of resistors and a handful of digital basic elements (no more complex than flip-flops).