Something else lifting with blocks does is put undo stress on leaf springs. You are essentially putting a block of rubber between the original mounting point and the leaf spring.
I have this on my yard plow, it was on there when I bought it. I guess some people think this makes the vehicle higher and makes you able to go threw deeper snow, mud, whatever.
It does not and anyone who tells you it does if full of crap. It does not raise the axels, ever burry your truck up to the axels? Lifted or not the axels stay the same height.
Now larger tires 33’s for example do raise the axels. This is not any safer for highway use but will make your axels higher and help off road clearance.