RIP anyone that drives a manual, tows, or goes off roading.
On a more serious note I’d imagine they stick around for diagnostics and inclement weather(forcing the car into a particular gear). Since the space is already there they generally have a bunch of other gauges and crap inside of them (all the warning lights that are usually off).
Once you have experience yeah…I rarely look at the tach anymore. It’s the process of acquiring that experience that it’s still useful also stuff gets loud or your driver might be deaf. Just helped my sister do something and part of the reset procedure on her car was hold 2000 rpm for 60 seconds. They serve a purpose is all.