In my more sensible moments, I remember that that idiot only needed to know HTML, CSS, the DOM model, Javascript, jQuery, HTTP (mostly headers and status codes), Ruby, Rails, basic MVC design, Oauth, SQL, SQL performance, five-ish APIs to support the two that needed integration, how to configure and maintain a server, system architecture, a bit of security, etc.
[There's also object oriented programming, class inheritance, polymorphism, algorithms, time complexity, discrete math, data structures, imperative programming, and a few other things I forgot the first time around. Lest we forget, we might take these for granted because we've been programming since we were $ARBITRARILY_YOUNG, but to most people these are just black magic. My girlfriend, a smart cookie, asked to see "how I made the phone ring" and, after I showed her the code that did that, told me it had never even occurred to her that every program she's ever seen was once a collection of special words placed in a particular order.]
After that, it was pretty much done, except for the marketing.
On the plus side: you can learn one or a few of these things at a time, and get more comfortable with how deep the rabbit hole goes as you go along. I coded my website in static HTML written in Notepad with no JS or CSS, crikey, only four years ago. (And my brain still recoils at how much better I'd have to get to do e.g. web scale work.)