Haven't read the whole paper yet, but below 600 Mbit/s is implied as being "Slow Internet" in the intro.
Meanwhile, low-end computers ship with a dozen 10+Gbit class transceivers on USB, HDMI, Displayport, pretty much any external port except for ethernet, and twice that many on the PCIe backbone. But 10Gbit ethernet is still priced like it's made from unicorn blood.
My understanding is right around 10Gbps you start to hit limitations with the shielding/type of cable and power needed to transmit/send over Ethernet.
When I was looking to upgrade at home, I had to get expensive PoE+ injectors and splitters to power the switch in the closet (where there's no outlet) and 10Gbps SFP+ transceivers are like $10 for fiber or $40 for Ethernet. The Ethernet transceivers hit like 40-50C
But switches haven't really kept up. A simple unmanaged 5-port or 8-port 2.5GigE isn't too bad, but anything beyond that gets tricky. 5GigE switches don't seem to exist, and you're already paying $500 for a budget-brand 10GigE switch with basic VLAN support. You want PoE? Forget it.
The irony is that at 10Gbps fiber suddenly becomes quite attractive. A brand-new SFP+ NIC can be found for $30, with DACs only $5 (per side) and transceivers $30 or so. You can get an actually-decent switch from Mikrotik for less than $300.
Heck, you can even get brand-new dualport SFP28 NICs for $100, or as little as $25 on Ebay! Switch-wise you can get 16 ports of 25Gbps out of a $800 Mikrotik switch: not exactly cheap, but definitely within range for a very enthusiastic homelabber.
The only issue is that wiring your home for fiber is stupidly expensive, and you can't exactly use it to power access points either.