I don't understand how this took an entire studio 6.5 months of engineering work? I'm probably oversimplifying but, start by running a local instance of the server, then point all queries to 127.0.0.1. Is it working? Great. Now make changes to the server or client as necessary to suit a single player mode. Like allow mods and such. Sounds like they are not keeping things simple, if that's the best explanation they have.

Wrong. I can't memorize my times tables either. I am consistently above average in my math courses, and am now taking second year math courses. Think again. Understanding simple concepts and memorizing formulas/terms/tables are entirely different.

This is hogwash. Education has nothing to do with memorization. Memorization is not understanding. Two entirely different beasts.