Perhaps the modern writers are merely reiterating what has been written before. Back in the 80's (I think is was) a prominent gun rag writer named John Whooters who had been to Africa & shot a cape buffalo with a .416 Taylor wrote that express sights were only useful for shooting charging game inside 25 yards and were useless for shooting at longer ranges than that.
When I read that, I laughed out loud. I had already been shooting under 2" 5 shot groups at 100 meters with mine - and with a muzzleloader at that. This was 1987, seems to me.
The best I can do now, (2 years ago) was 2 1/2". Getting too long in the tooth, I guess. LOL- 4 of them were in an inch.