Earlier quoted context omitted.
C&C is a clear counterexample however: all units can be selected as a group. That is to say: pathfinding was fast enough that it clearly wasn't a problem in C&C. But they clearly wanted to nerf infantry-based death balls. And boy oh boy, are infantry-death balls nerfed. An occasional infantry unit still finds its uses in C&C. They're incredibly cheap after all, and tanks have a difficult job killing infantry with the…
I find that scattering rocket soldiers randomly about the map and one's base is a far better and cheaper anti-air defense than building dedicated SAM sites. A small investment makes aircraft almost useless. But I'm pretty inexperienced at the game.
Advance Wars has a bit of a rocket-troop deathball problem however. Rocket troops are so cheap and effective, that large masses of rockets overpower any possible opposition.
Its clear to me that C&C had designed the "instant kill squish" effect to mitigate this problem. Maybe in playtesting, they tried it out and realized that rocket troops are just too powerful. A singular unit that truly does everything at very, very cheap prices.