In an ideal world, you are right, and someone with reasonable literacy can read and follow those instructions, and that’s what I recommend to anyone needing social logins.
Navigating the create your app gauntlet on many of those sites is a little confusing if you’re not adept at such, and fiddle even if you are. If you’re someone like me, configuring it for someone else, do you create the thing under your own account, or get their credentials and do it for them?
There was discussion here recently, of fairly technical folks, who weren’t sure just what google wanted. (Configuring Google login for Discourse)
Maybe I’ll check it out again tomorrow and see again just how big a pain it is for a couple of my sites, but as I recall it’s fiddly enough that I would hesitate to do it for someone for less than $50 to $100 per social app, so that’s nearly $500 for all of them, which seems like more than someone would expect. Still, I could do a dozen $99 installs in less time than it’d take to configure a single Facebook login.