It's still a thing. It's a pain in the arse because it uses a carrier on the mains that has harmonics on every HF amateur band, that radiate from your house wiring for a couple of hundred metres.

Some of the sites I look after at work still have modems attached to the incoming electricity meter from a Broadband-over-Power-Line trial about 15 years ago. It wasn't very fast - it was supposed to be 200Mbps but struggled to do 20, and was often more like 2Mbps - and it radiated RF hash everywhere powerlines ran, from about 500kHz to well up into the hundreds of MHz. What eventually killed it in NE Scotland here was it splattered all over marine VHF, in an area with lots of marine traffic like oil platform supply vessels.

TL;DR anything that uses basically RF over unshielded untwisted cables that radiate everywhere is inefficient and antisocial.