As is MoCA, which in my experience is a lot higher-speed and more reliably so.

People tend to want speed, speed, speed, but tons of use cases are totally fine with a reliable 100 Mbps. For a lot of remote monitoring stuff, even 1 kbps is enough if it works reliably. Not everything needs to serve up a webpage.

Yeah I have tried it! It beats WiFi to some rooms, but to my office it's very slow.

You would never be able to predict this, which is an unfortunate thing about powerline IMO. You just have to buy the modems and see how they perform on your particular wiring.

Do you have personal success using powerline ethernet? I tried it once and it was utter shit.

A very expensive "up to 1000mbps" kit maxed out at ~200 when both devices were plugged into the same outlet. It just got worse with distance.