[maxyme]

Because gigabit wifi turns to 50mbps when the office gets big enough. There is only so much spectrum to use. Plus if you're already connecting monitors when you have your laptop at your desk the Ethernet adapter can be part of the dock.

[cbhl]

When the office gets big enough, you reduce transmit power and add more access points so that there's enough spectrum to cover each desk.

Aruba Networks equipment was used at my alma mater, and is also used by $dayjob. I've also had good experiences with employers using Cisco Meraki.

[zamadatix]

Even a single AP, single client, 160 MHz AC wave 2 2x2 connection in clear airspace has less max theoretical throughput than a gigabit hardware (1.7 vs 2).

What makes a sane high density 5 GHz office design with 40 MHz channels (theoretical 400 mbit/s, real usually ~200-300) work is that office workers don't actually need that decent of a connection, just a guarantee voice jitter won't be >10 ms and that throughput will be "fast enough".