Because reduced load shoot better in the .44 Special than in a .44 Mag case.
Own both and the difference is clear. Tested dozen and dozen of combinations, and the .44 spl always come on top for accuracy. Sometime not by much - but always more. Same reason PPC guns are chambered in .38 Spl and not .357 : accuracy edge.
I do not understand people who buy a Ferrari and run it at 30 KM.
Same with the .44 Mag. Most people shelves it because of ammo cost and recoil or seek reduced load.
In.357, most people end up feeding them .38 Spl.
.44 Spl. guns are just right. Not too heavy..and shoot great. Right case size. Remember the .44 Spl can be loaded to .44 mag speed..but no need to.
Shooting full magnum load is fun for a time,. 454 Casull .460, .500, 45/70 too, but everybody finish by dropping them and go with caliber that offer more practical accuracy and a more pleasant shooting experience.
The .44 Spl fill the bill nicely.
If we were allowed to hunt, the.44 mag will not be my choice. The .460 or a .500 Linbraugh will be it. But then, you do not shoot 100 rounds of those at target paper..