from my guessing, infinite chakra means they cant do anything they couldnt do alive, but they dont use up any chakra doing so. hence why deidara couldnt add tons of chakra into a bomb and "art" the entire shinobi alliance.
He split himself in half (different from shadow clone division) and this halved the overall chakra pool available to each half and rendered him incapable of using his most chakra intensive Jutsu