One weird use is that despite its flaws, the DIY ergonomic keyboard community has pretty much standardised on the four-pole 3.5mm variant for connecting split k

One weird use is that despite its flaws, the DIY ergonomic keyboard community has pretty much standardised on the four-pole 3.5mm variant for connecting split keyboards together. The wires carry DC power and serial! It got chosen because it was compact, it can be repeatedly plugged and unplugged, sockets can be through-hole soldered, and double-ended cables are widely available. There is no obvious alternative with those characteristics, and they outweigh the bad.