It's called that because 20 years ago when the guide was first written there was no Gmail or any comparable service of that magnitude. Sure you had GMX or Hotmail but most people online back then had an email account hosted by their ISP. That was the most common way to get access to email.
The ISP Mail guide describes how to set up a mail server infrastructure similar to what an ISP mail service would provide, back then.
NFC isn't going anywhere, what are you on about?