Then you've clearly never edited video or moved around a disk image of a virtual machine, or anything else that will tax your patience copying 5GB over shoddy wifi (nevermind things much larger than 5 gigs).
Yeah, you're right, he hasn't. Thanks for the reiteration. Not everyone uses a laptop for the same things you do. For the stuff you're talking about I wouldn't dream of doing it away from a desktop computer plugged in to GigE. For me, and many others, the sole purpose of a laptop is portability. I couldn't care less if it can't do what my desktop computer can do.
Although, if you are performing serious work loads like that, why not just take the 10s to plug in the Ethernet cable? It seems like for these use cases you already would be using the laptop with the power cable hooked up.
But that would be over internet, not over the local network. And internet is slow on average.
You can still connect to a local network via ethernet