i think you need to check the definition of strategic warfare. it is literally denying your opponent resources crucial to victory. heres an example: lets say my army is stationed at the top of a hill. my opponent is trying to blast me off using artillery strikes. to thwart him, i send a garrison 20 miles down the road to destroy his ammo depots. by removing his ability to bomb me, ive strategically kept the hill.
now, lets do the same scenario, but using tactical combat. instead of attacking his resources, i use the same garrison to flank his army from the left.
think about it like this. tactical warfare is like fighting in a big fishbowl. nothing outside the fishbowl has any affect on the battle. only the soldiers and units inside have any purpose. strategic combat takes things outside.
chess = tactical combat
risk = strategic combat
every attack plan you mentioned falls under the realm of tactics. dont get me wrong, im not saying one is better than another. my point is that by military definitions, chess is a game of tactics.
therefore, there is infinite amounts more strategy in warcraft than in chess. however, ill concede that the tactical combinations in chess dwarf any other game out there. though personally, id still rather play warcraft :/