Well, my wi-fi is unaware of your arguments, and continues to work perfectly. If it didn't, I'd go back to the powerline units I have sitting in a drawer gathering dust.
I just ran an Ookla speed test on my phone and it came out at 50MB/sec as far from the router as I could get.
I am on Virgin Cable at 150MB/S so it's a third of that speed but that is plenty for what I want. It might work even faster on the 5GB band, but I can't be bothered to try it.
One point about powerline units is that you will have only one connected to your router, and that will constitute a bottleneck just as the router does for wifi. The two - wifi and powerline - are very similar in the way they work as far as the user is concerned. the only difference being that powerline is confined to the powerline, and even battery operated gadgets, therefore, need a connection to a socket. Sometimes this is not an inconvenience, but often it is. I recently bought a colour Laser for a mere £80, and wireless is built into it. It works beautifully. I doubt you'd get a pair of powerline connectors plus the cables to connect to them at that price!
It is worth considering too that wi-fi is everywhere these days. I can access my home network from the local Pub
or on the bus if I want to. Not that I do very often, but I have used it in a hotel - using their free wi-fi and my tablet - to watch a movie stored at home on my NAS for instance.