I mean like it'd be harder to destroy a gem. Just stepping or crushing the stone in your hand wouldn't be enough. Plus the gem could just easily reform in a few minutes.
And we don't know how humans were involved, as Greg never specified. They could've just been casualties, they could've fought for one side or both. Frankly I think it was a mix. Most humans stayed out of the war but some went and fought, probably on the Homeworld side as Homeworld probably promised them stuff and portrayed the CG as bad. Maybe humans were experimented on by Homeworld. Don't know but it's a nice thought.