I guess I should’ve read farther down, but I’ll add this- I don’t think federal prosecutors employ overcharging to the same effect as municipal prosecutors.
I think the real effect, as others have noted, is stripping contextual discretion from federal prosecutors. Sometimes the highest charge possible doesn’t accurately portray the context of the crime, particularly dangerous here is ‘highest charge’ is qualified as 'longest possible minimum sentence, and many of the federal sentence guidelines are arbitrary as fuck.