Home internet in the 90s felt simple. You plugged into [Ethernet](https://en.wikipedia.org/wiki/Ethernet), got an [IPv4](https://en.wikipedia.org/wiki/IPv4) address, and you could expose a service directly. Today the path is layered and driven by economics. IPv4 did not end in a hard way. It became scarce and costly, see [IPv4 address exhaustion](https://en.wikipedia.org/wiki/IPv4_address_exhaustion). Data centers and enterprises still buy and route IPv4. Most residential users are placed behind [Carrier-gr...