Shanks didn't really need them to guard his rear if we're being honest. Their AoE is at least island level even pre-TS and Oda has likely buffed them with haki and such. Even still, I can't see them beating any of the worst gen in a 1v1, but they have proven that giants are not just samurai-fodder, probably slightly less powerful than ashura-doji.
They need to be hyped though because as far as I'm concerned they actually upstaged Shanks with what they did, an attack on their home was met with utter annihilation. Doubt Kid could have blocked that attack even if he hadn't just been clapped by Shanks.