It wasn't spammed because there weren't many places to put them. Go and try it. You can't demo anything but buildings and enemy emplacements. I even tried building my own tank traps in order to have a structure to blow but it didn't allow placement there either.
Commando demo is diff. Place it anywhere. Same 50 munitions, still very powerful, no research, and like the US demo it provides some vision around it.
I don't need to try it, I always used it, and it was brutal against a german base once you sneak in at the right time.
Here is one example where engineers do a demo rush and get out alive commando style!
Relic Entertainment
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