Mostly because of the way GM trucks are designed. I haven't looked at new GM trucks in a few years (both GM dealers in the nearest towns have shut down) but pre 2020 not only not only did stock GM 2500 and 3500 trucks not have anywhere near the ground clearance under the middle of the truck (frame hangs much lower) that a Ford or Ram has, but there were all kinds of cables hanging down below the frame also. I remember reading a test in one of the truck magazines and they made a point of talking about the low-hanging stuff. If it were a diesel model the DEF tank was located right behind the passenger side front tire and it hung down so low it would frequently get crushed or punctured. And stock the IFS is not as strong - I attend truck pulls and in several of them I watched the front ends break on a GM pickup when all that power (nothing wrong with the Duramax!) was applied. A few years ago I came across an accident on a dirt road where a Chevy 2500 front end came apart and the truck, towing a stock trailer, crashed and a horse was killed. Similar to what happened below but in this case the top A frame failed and that corner of the truck dug into the dirt, sending it out of control.
On the other hand, the GM trucks normally drive much nicer going down the highway. I've never driven a solid front axle truck that didn't wander a bit even on a smooth highway, and they don't respond to steering inputs as accurately. IFS always drives smoother over rough roads also since what affects one front wheel doesn't affect the other front wheel.
If your driving is on good roads a GM with IFS should work just fine.
