I'm lucky to hunt on my land where I have intimate knowledge of property size, dimensions, shape, etc. from being on it for past 30+ years. Despite this I always carry a laser range finder when I'm hunting out in the pasture as range can be as far as 800 yards. I can range animals out to maybe 300 yards just by the landmarks and angles but for most people anything more than 200 yards and they are off by 25% or more.
Most people don't shoot very much these days as they all have buy life. Also for those in urban areas it is getting more and more difficult to access shooting range. I have a shooting range out behind the house where I can shoot out to 500 yards and I shoot couple times a week but that's rare for most people. Instead of practice shooting they rely on the equipment to make up for the deficiencies. I see a lot of guys with very little skill but very expensive rifles and scopes...but they still can't shoot beyond 100 yards.