The problem is also that the Dakka each individual Guardsman provides is very limited. So while you have a theoretically infinite amount of Dakka, it would still not be ENOUGH. Because it could be infinte Dakka that's also stronger.

Real question is how you're getting those guardsmen all into one place. You'd run into space constraints before you got enough guardsmen for enuff dakka. You'd need too much material to make your guardsman launcher.
If there's one thing Guardsmen can do, it's standing in one place, tightly packed.