That is the concept of the low mag power, forward mounted scout optics. Very fast acquisition for targets that might pop up quickly.
I get that. Now look at the picture in the post I quoted. Doesn't look much like an IER scope to me.
A .45-70 does not have a flat trajectory, but it hits hard. It is an optimal cartridge for two things: closer shots on large and/or dangerous animals, and long-range shots where you can take your time and compensate for the drop. Either way, it's not a varmint round, and absolute accuracy is secondary when you're shooting really big game.
And no, you don't shoot buckets offhand at 1000 yards. You may, however, shoot buffalo with shooting sticks at 300... For which the .45-70 works as well as it did 130 years ago, with the same sights.
The IER scope is a wonderful addition to a short .308, which shoots flat enough for quick point-and-shoot use at 0-300 yards, maybe 275. That's a great match for a low-power, forward-mounted scope.
That bears no resemblance whatsoever to the optimal use of a .45-70.
Now, very poor eyesight is a good reason to get a scope. But my eyesight isn't the greatest, and I still wouldn't want to put one in a Guide Gun. Defeats the purpose of the powerful little thing.