the 6 50cal package is one of the best gun packages in game. You obviously have never done proper buff hunting in a P47.
It is popular as it was major gun package at us planes, but it never was one of the best - neither historically nor in AH.
6x.50 is good enough against fighters - because it has good ballistics and rate of fire but for an average pilot it is insufficient for a bomber. US fighter never fought against medium/heavy bombers so they didn't need heavier caliber weapons.
Against fighters I personally prefer central line oriented weapons that make much more concentrated fire like at Yak-7/9/3, La-5/7, P-38 or 109-G6/G14 - so if you hit you hit hard even if you not at exact harmonization distance.
Against buffs the best are German weapons set with multiple heavy 30mm or 20mm.
Of course it is more than possible to kill a bomber with 8x.50 cal but it is far from perfect weapon. Finally you can even kill a bomber with 8x.30 cal successfully