[Mecha anime and RPG's] Why don't I see as many mecha teams as I do RPG adventuring parties?

Like the giant robots are just scaled up, mechanical physical fighters, including warriors with their melee weapons and heavy armor, and rogues with their ranged weapons and light armor. With the closest mage or cleric analogues I'd usually find among them being either home base support crews or assault carriers. Which means it's possible to have a team of five specialized mecha units, including a melee, ranged, heavy, light, and general-purpose unit each, e.g. the Wing boys and their Gundams from Gundam Wing.

So why do I see more solo ace mecha than I do small teams of them, compared to adventuring parties in a medieval fantasy RPG like Dungeons & Dragons, Dragon Quest, and Final Fantasy?