I agree with the take, unfortunately the new construction with Fiber to the home, this becomes less and less feasible, since ISPs expect to have routers with the fiber cable input as WAN port.
This is the case of Iliad in Italy.
In Germany you have FTTH installations where Telekom puts a mini Fiber Gateway in your home and an extra router dials with the credentials to access the internet. In this setup, you can use OpenWRT or other routers, rather than the Fritz!Box or the Speedport routers.
As long as there's a reasonable way to get an SFP module, there's a good amount of routers with those sockets and I can get a gigabit media converter for $20.
When it's shrink wrapped?
And why would a used device be on the shelf next to the new router I was buying?
You can argue this is "just as likely" with used devices, maybe. But if I'm buying a router it's not going to be used.