It's easy, simple, reliable, less parts to break, less to go wrong, and it works. FX3 6x42 with an added CDS (standard dial and not load specific).
I ended up going that way because most of the time I hunted I kept my scope on 5x-6x anyway. My closest was 20ish, longest 430, average shot was around 173 yards I figured a while back, don't need anything really low or really high.
It isn't ideal, but will work up close. Isn't ideal at long distances, but I easily pop rocks in the 400-500 range and all the way out to 589 so far. From 200-400 has been too easy. I do wish for more X at the range, but when I'm averaging sub .4" groups at 100 with my best of .189"... I guess I do just fine and anything else is just for bragging and not hunting.
Why do they still exist? Because they work and people still buy them.
I like to keep it simple. For big game hunting I use one rifle, RBros 280AI. I use one load, 55.5 IMR4350 145 LRX. I use one mag on the scope, 6x.