The thickness of the metal in the barrel and the slide is why.
I personally run a Glock in open, but after mountains of research have decided to stay away not only the safety/ reliability factor but in the end the lightness of the gun makes the gun recoil more than 200% more than say a heavy gun like a steel framed 2011, ipsc is shooting alphas as fast as you can and personally the benefit of major gets thrown out the window once you figure the recoil going with it in a Glock platform, you will score better and faster with a minor glock.
I use auto comp and a ported barrel and the gun is stupid flat, which means you can double tap alphas instead of pulling regaining sight picture then pulling again. Now I still have a slide mounted reddot so my sight disappears every time I pull the trigger, but the gun is so flat it goes right back and I can pull again quickly and it sounds like a double tap. Just my personal opinion..
if you’re interested in seeing this setup run
on Instagram thanks for the listen.