I guess it comes down to what they are shooting and at what ranges - I know some who find that loads that shoot ok at say 200 or 300m aren't as accurate at 1000m hence they make loads that shoot well at those distances.
Me I don't shoot fur much over 300m so my loads are generally good enough for that and generally good enough for the shorter ranges too.
Different bullet designs will effect accuracy over long distances as will barrel length, powder, etc. Round nose bullets are often used for very long range with lower velocity cartridges but also with some higher velocities too.
There's still a few of Wile. E Coyote's ideas that I haven't tried yet.
I shoot Fullbore, from 300 to 1000, rotating thru each range on a weekly basis (except at prize meetings where u will shoot the lot over few days) I use the same load for all, and don't know any other Fullbore shooters who don't do same.
A question that would take a book to answer properly . Yes a certain load can be more accurate at a longer range due to many factors some relating to dynamic stability being bad early but settling down later . Rifle barrel displaying positive compensation . Generally the whole idea to a short range load and a separate long range load is more about cost . The long range load will be the more expensive ammo and the shooter may not want to shoot them off at 100 yards at beer cans or rabbits Off course if the long range load is good at 1000 yards it's generally also going to be very accurate at shorter ranges in 99% of cases but not In every case.
I don't do any long range target shooting. As Scott says only up to 300m but I would thing that a load that was accurate at 100m would be also accurate at 100m. However boattail bullets tend to come into their own at ranges past 250 or 300 so perhaps that's what was meant. JD
If it's not wood and blued steel, it's not one of mine
I suspect the people you've read saying as such are long range target shooters.
As Warrigul indicated, to stay super-sonic a extreme ranges you need hot loads and high BC/low drag bullets. Dropping from super-sonic to sub-sonic mid flight degrades accuracy so is to be avoided.
This ammo isn't going to be the cheapest and the recoil may also be particularly unfriendly, making it a bit of a waste for shooting at more moderate ranges.