Does the "large actor receives pre-shadow" warning apply when not using static shadows?

I have some large instanced static mesh actors that have tons of individual trees in them.

I’ve turned off static shadows/lighting – I’m only using dynamic lighting.

When doing a Map Check, I get the warning:

InstancedFoliageActor_0 Large actor receives a pre-shadow and will cause an extreme performance hit unless bCastDynamicShadow is set to false. 

Clicking the “docs” link takes me to this page: Map Check Errors | Unreal Engine Documentation
That page actually doesn’t talk about this error!

Reading up on when this error happens, it sounds to me as if it might not be particularly bad for dynamic lighting/shadowing? Or maybe only actors, not individual instanced components, get culled for purposes of shadow map generation, and thus the entire forest is rendered into the shadow maps? (Guard band clipping can only go so far on helping with that, after all …)