You're right, but you're wrong.
Let's take a car as an example.
MaNGOS is the constructor. Gives you the engine, car body, windows, etc.
But after that, you need a lot of thing to drive your car : gas, engine oil, washer fluid, tires, etc.
UDB, YTDB and others provides you all these things. As Shell, Exxon or Total does for your car.
You need to feed your core. Give him something he can work with.
MaNGOS is not (fortunately not yet) a "launch and play" software that your blind little sister can install in 30 seconds.
"No wonder people are so unhelpful around here."
You're right : nobody takes the time to understand what is really MaNGOS, so they yell on forums "NOBODY HELP ME MANGOS SUCKS". As if the whole world owed them something.
Later, people who used to be helpful are just tired and stop being helpful.