Generally they connect directly to large back bone transmission lines that carry power far beyond the local area though not directly to more balkanized power zo

Generally they connect directly to large back bone transmission lines that carry power far beyond the local area though not directly to more balkanized power zones. On a large scale yes if critical junctures go out the rest can't take the full load but that's different than a single plant being overspecced for the transmission capability it's connected to.