Sure can buy them but factory rounds are mass-produced so the SD (standard deviation) in muzzle velocity is too great. They vary too much and at long range that matters - They act unpredictability. Also there is no way to determine what the actual load is and the seating depth of the projectile varies too...The primer depth too. Loads of reasons. All of these factors are calculated into a FFS (field firing solution) when a long range shot is made. Long range being 400-1600m.

It's also wasteful to single-use brass. Reloading it 5-8 times, until the brass is no longer structurally sound, is way cheaper than buying factory rounds by about 50%. Leading up to a competition, and in the comp, I may shoot 1000 rifle rounds at about $2.50 a shot for factory...Half that for my precision reloads.

There are so many reasons for reloading...

I also think it's a cool skill to have.

Hope that helps.