The manufacturers bring to market what they are relatively certain will sell. I don't blame the ammo companies for that, I blame uninformed shooters.
Fred Kimble's shotgunning should be studied closely by every bird hunter. He shot some magnum loads, but at lower velocities. That's what the term magnum originally meant . . . a heavier than normal payload, not necessarily crazy high velocity.
Density on target, with the needed kinetic energy, is what kills birds. That can be accomplished often with tighter chokes and standard payloads, at longer distances.
