When I get a Cisco router with an integrated CSU and the telco sends a loop-up my device does it. No reason the same can't be done with ethernet, other than no demand today.
But your router isn't where the Telco's responsibility ends. It ends back at the card with the blinky-lights on it, usually mounted next to the protector block at your MPOE. It's the DS0/T1 equivalent of the ONT. (They can also send test signals to it as well.)
I would like to build an infrastrucutre that could last 50-100 years, like the telephone twisted pair of the last century. The only tech I can see that can do that is home run single mode fiber to the home. Anything with electronics has no chance of that lifespan. Anything with splitters and such will be problematic down the road. Simpler is better.
An interesting claim given that the Telco twisted pair you are holding up as a shining example did involve electronics, splitters (known as bridge taps) etc. Owen