To power up over a network would need the Ethernet and/or WiFi powered up and a computer running to listen for the command. There are requirements (look up ENERGY STAR) when the power is off that means that this can't happen. The old IR system was very low power so that's why that worked back then and now.
So in the big scheme of things, all you wrote sounds right. Bluetooth might be low power enough but very few sets would have such.
I have always used IR based remotes to control my Samsung TVs. My last phone was a Samsung S6 that had an IR blaster on it. I was able to use the Sure Universal app on my phone to control my TV and Amazon Fire Stick. Now with the S8, there is no IR blaster anymore. But...I can connect to the TV wirelessly (it connects and gives me a code) and everything works great except the power button. The power button...no matter what...will not turn on or off my TV so I must physically use the button on the TV to do that. I don't have the original remote anymore.
I guess my question is whether or not Samsung TVs made in the last few years support wireless control of powering on and off? I don't know if this is a limitation of the Sure universal app on the phone or just that Samsung TVs only support certain functions through wireless control.

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