Maybe because many streaming services have locked their 4k content behind some specific apps and platforms and offer lower resolutions on general desktop PCs.
If it's all the same driver board, they save on complexity of having different parts. I hate it but it's true. Samsung gaming monitors now have to keep track of a remote to change settings.
Both HDMI and DisplayPort feature USB/Ethernet data link capabilities, and obviously USB-C does as well.
This is dependent upon the version of the cable, and all other hardware involved, but this is well within the bounds of available ad/surveillance tech.
Their TV does but I'm not sure how it works with monitors. Maybe it's just hardcoded ads in their software. I don't see how the monitor can have a network connection..
Ethernet over HDMI
Ethernet over display port
Ethernet via thunderbolt
They could probably do something tricky with a driver and serial over HDMI
I don't know about this one but several LG monitors actually have Wi-Fi built in.
Of course, If it was using Wi-Fi you could just not connect the Wi-Fi. But some manufacturers are getting smart and are able to use open networks to call home. You could open it up find the antenna and short it out directly to the ground plane