This is pretty ridiculous that this editor is so complicated Ih ave to ask something that was super easy in StarEdit but...

how the fuck do I do something as simple as saying Current Player controls 0 buildings, end in defeat for Current player

The reason you are having such difficulty with this is because some things are done very differently than SC1. In SC2 defeat triggers like the one you want are (more or less) built in, you just need to activate it. Using the Enable/Disable Melee Option For Player action should allow you to do want you want. Enable defeat for every player you want the defeat action to happen for.

To edit what prevents a defeat go into the data editor and look at a unit you want to prevent a player from being defeated. Under the flags setting there is a Prevent Defeat option. If this is checked then the unit will prevent the player from being defeated. By default all buildings have this flag checked.

Copy the above code and paste into the input box at http://vgshorts.com/BBCode/BBCode3.php . Hopefully, this post will help you understand GE a bit more.

In GE, the difference between an Event and a Condition, especially when compared to the old SC1 Conditions, are much more different, and some things that were easy to do in SC1 will require a bit more ingenuity to implement in SC2, but likewise, some things that were literally impossible with StarEdit can easily be done in GE, such as detecting when a unit is attacking or getting damaged.

But, yea, I had that exact same reaction a million times with WC3's WE. ;o