Why RTS games will always be broken

Ok, I know that's a provocative title. RTS games are an awesome genre, they can be very well balanced, and they can be really exciting to watch. They can be very deep as well. But strategically, they are broken in a fundamental way.

In any strategy game, there are two universal advantages: material and tempo. Material advantage means having more useful things, usually men or resources or buildings. Tempo advantage means you've accomplished more useful things than your opponent. There are many other game-specific advantages, and it's those advantages that give material and tempo advantages their weight, but these two are nearly universal.

I say nearly because they don't apply in impartial or shared-material games like Sprouts or Dots and Boxes. When in doubt, I will refer to Star Craft as a well known and fairly quintessential RTS.

One prominent characteristic of the RTS is that material and tempo are nearly equivalent. Building material requires resources (like minerals) and time. Getting resources takes material (a resource-farmer and usually a resource-dump like a command center) and time. Since starting material is usually farmers and a resource-dump, resources are nearly identical to time.

To speed resource gathering, you can build more farmers, or you can build another resource-dump. Both take resources and time. A material advantage in this form directly translates to a tempo advantage.

If I destroy 1 more of your fighting units than you do of mine, I have gained more than a 1 unit advantage: I am now ahead by the amount of time it takes to build that unit as well.

A tempo advantage can be converted into a material advantage by building more units or unit producing buildings, and a material advantage can be turned into a tempo advantage by destroying your units.

This can be mitigated by offering advantages that are not fungible. The most obvious one is a unit-type advantage, where one unit-type wins-out against a different unit-type. Requiring or allowing a number of non-fungible sub-goals towards victory is a simple first-approximation for adding depth to a game.