Doesn’t change that the bandwidth for Z-Wave is tiny, and it’s a mesh, both of which means it’s not well suited for large amounts of data, like high throughput sensors (of which power reporting is one example). I have four dozen wifi devices and really don’t have any issues, I think it mostly gets a bad rep from people who a) use 2.4Ghz for other devices (I put only IoT on 2.4, everything else is on 5Ghz) b) use shitty home gamer access points instead of something decent like Ubiquity/Microtome/TP-Link etc.
You can be pedantic if you want, but it’s pretty obvious OP meant RS232 serial.