Sorting handgun brass by headstamp does a few things to benefit me, and I will list only the ones that I am CERTAIN of:
--in the most critical phase of the three totally different dies, sorted headstamps give me extremely consistent feedback in my press handle. That is, the seating & crimping. There is a particular resistance and feel that I recognize (easily) and demand when making my ammo. If you use a myriad of headstamp, expect no consistency here whatsoever.
----subpoint: if you chronograph handloads you can see how much the result is impacted in some rounds when the bullet pull/case mouth tension or simple "grip" on the slug varies. In heavy revolver rounds with slow burning powder, a solid & consistent crimp is paramount
----subpoint: in semi-auto pistol rounds, a pistol is by it's very nature an extremely harsh environment and rounds without solid bullet pull/case mouth tension can lead to unintended/unnoticed bullet setback. The result of bullet setback is a radical pressure spike and can be catastrophic. When you get the feel you look for and demand when seating bullets, you NEVER have the mystery of "sufficient bullet pull?"
--all of THAT removes doubt, inspires confidence in my ammo... easily and consistently contributes to more confident shooting, better results
--all of THAT and a box of 50 rounds that look the same and felt the same during assembly offers simple pride in a job well done, satisfaction, and extreme confidence in the ammo. Makes it easier to focus on the firearm and the shooting-- worrying or evem casually wondering about the ammo is out of the equation.