I mentor and teach a lot of designers and beginning front-end developers. Services like this and FormSpree are a godsend for allowing them to create functioning contact forms on websites without having to go down the server-side rabbit hole.

Also, even though I'm fully capable of building my own form handling back-end, if I'm just building a static site it's nice not to have to deal with all that just for a simple contact form.

Um no.

This is for when you don’t have a server.

It will probably be something that compiles to javascript made with babel.

New tools solve problems, but create some new (hopefully smaller) problems, which opens the possibilities for new solutions.