Lagless ledgehopped dair landing only gives a 6 frame window for the opponent to do anything, which is being cut even shorter by the hitstun the dair's multi-hitbox causes. Fastest thing they can do is shield, and a shield can be grabbed: They're eating the grab.
And stop nitpicking at usage of words! I'm saying, and have said, that the "combos" I'm talking about are the strings of successive attacks done by following the reactions of your opponent. A ledgehop dair > grab is practically assured, all that might ruin it for you is if the opponent shields the dair, or you miss where you're supposed to land... I know what the true combos you're talking about are, but fact is, Kirby has some too. And in Brawl, the general term used to string attacks is called "combo". You're just gonna have to get used to it rather than correct the majority of people. :/