Lots of "just use X" comments but the article is about showing the bare minimum/how easy the core part of routing actually is.
Also, if you have ever used docker or virtual machines with NAT routing (often the default), you've done exactly the same things.
If you have ever enabled the wifi hotspot on an android phone also, you've done pretty much what the article describes on your phone.
All of these use the same Linux kernel features under the hood. In fact there is a good chance this message traversed more than one Linux soft router to get to your screen.
Also, if you have ever used docker or virtual machines with NAT routing (often the default), you've done exactly the same things.
If you have ever enabled the wifi hotspot on an android phone also, you've done pretty much what the article describes on your phone.
All of these use the same Linux kernel features under the hood. In fact there is a good chance this message traversed more than one Linux soft router to get to your screen.