^^ as PPs explained, I read a lot of arguments about WM NOT accepting Target store coupons like $2 off on Revlon cosmetics. I don't see why shoppers should argue about this when this is clear in the policy stated above. Problems usually arise when shoppers start comparing their shopping experiences where some will say they can get away with whatever they want since THEIR store allows it.
With that said, IF WM terms and conditions on coupon use can be summarized in 4 letters,
official policy is YMMV.
Find a need and fill it. There is unlimited opportunities out there for those who diligently seek them.