The most useful monster.

That's the point... there aren't any that are better... Each one is good in a specific situation... Don't you agree?
And the phrase isn't memorized... it's self-generated.

No, I don't agree: because there are simply personal preferences! For example, some people might enjoy the stealth of thieves, while others prefer a djinn-illusionist. There's always something that a particular unit did that caught someone's attention, and now it's a staple in almost all tactics for playing as that faction.