Part of the trouble with fillers is that as a position sensitive, inert material inside the case, ammunition handling can cause shifting of the filler, comingling with powder, etc. This is probably no threat to a well-assembled load that is very carefully handled and fired on the range, but over time and general use may present problems for hunting ammunition.

The real question might be why use them in the first place? Skilled handloading precludes their need under almost, probably all, circumstances. Fillers are sometimes a crutch that further experimentation proves unnecessary. As for 5744 {and the similar 4759}, it serves in many cases to totally preclude the need for fillers.