i dont see how someone who has never used buckshot can come to a conclusion that buckshot is only effective under 20yards

i have used #4 buck on jackrabbits, coyotes and cats out to 50 yards and most have died after running 40 yards or less. rabbits are usually bang flops.
buy the premium buckshot loads and you will be able to down deer at 40 yards IF you find the right load/choke combo for your gun. the fact is that most shooters dont spend the $$$ to find out which combo works best in their gun so they automatically assume that buckshot is junk.
another well known fact is that many hunters are brutal when it comes to range estimation. if everyone used a rangefinder then more people would like buckshot because then it would be used at the appropriate ranges.
i do not use buckshot for deer because i have a rifled barrel. but, if i didnt have the rifled barrel i would have my gun loaded with #1 buck in thick stuff where shots are usually 40 yards or less.
btw.....22lr or 6mm is the same diameter as #4 buck. 000 is .35" i believe or 9mm.