I've been running Web sites for about 15 years now, and BBS'es before that. Way back in the BBS days, I used to have a favorite (VBBS, aka "Virtual BBS") which offered Basic developers an "SDK". This SDK was essentially a file of libraries and code which -- when you understood how to code in Turbo Basic -- had a file which literally said;
"---- Your code begins here ----"
"---- Your code ends here ----"
What that SDK provided was a system of all the calls in the system on which you could pull. You wrote your subroutines between those two lines, added it to the modules system, and bingo-bango-bongo, you were a bonafide VBBS module/game developer.
(If any of you were around back then, I wrote v-Shell which allowed a BBS operator to log into their account, then access VERY limited OS calls, like directory listings, moving/copying files, launching tape backups, etcetera with what was then, complete security).
Sorry for the history lesson, but I do have a point.
Granted, Turbo BASIC was 1000x easier than PHP/MySQL, but over the years, I've become a semi-competent "Bedroom" PHP/MySQL coder. Not great, but able to code my way out of a paper bag (so to speak).
The one thing that I think Xenforo could offer that NO ONE ELSE DOES which would instantly create thousands of new Xenforo coders is exactly that type of library set, along with a Word file documenting the system calls necessary for the average idiot to write good, solid modules.
At the time (almost 20 years ago), I paid $99 for such an SDK, and I'm not sure it'd be worth "$500" now, but if someone could take the time to build one for all us hopeful Xenforo developers, I am absolutely certain that Xenforo would literally explode with add-on development, driving sales of the add-on package market, as well as more license sales of Xenforo.