When game departments put in ML hunts they are limiting technology. They don't want 1000 yard rifles with 20X scopes. As is the case in Idaho they limit the acceptable rifles and gear.
That said, you listed a MK85. That rifle is quite capable of shooting to 200 yards accurately.
This is an MK85 that is legal under the Idaho laws.
This is a picture of my son shooting that rifle at 250 yards.
That rifle shoots a paper patched bullet that is sized to fit the barrel.
This rifle was built about 10 years ago. It also is a Idaho legal rifle. It is accurate out to 300 yards.
It shoots a paper patched 11mm rifle bullet.
I have other rifles that I built well over a decade ago that are more than capable of shooting to 300 yards.
There have been muzzleloaders built that will shoot to 1000 yards and they were built in the 1860's. Those rifles are still made today and they are still shooting 1000 yard matches with them. New companies with ballistic calculators and all the bells and whistles were not even thought of yet when the Whitworth rifle was shooting 1000 yards at targets.
But even with those super accurate rifles the shooters still have to develop loads. Yes there is a lot of info out there on loads and bullets and shooters have a lot of options and help available that guys back then just didn't have.
My load for the MK85 and other fast twist rifles, is about as turn key as a load can get. It has worked in every gun I have tried it in. The secret is there is no plastic to foul the barrel. There is no lead to foul the barrel. And the bullet is protected 100% until it leaves the barrel.
And last the sights are adjustable for the shot at hand. If the shot is 75 you set the sight for 75. If the shot is 135 you set the sight for as close to 135 as you can. In all cases you aim dead on no hold over. This is technology that was around back in the 1800's.
The info for this system is here on this site. It is also in many places on the internet if you look me up. Also I have video's showing making the bullets, shooting the gun, cleaning the gun care and maintenance. I have been giving away this info for a dozen years. Many guys have used it to make their rifles shoot better. Once and a while I get a guy that wants me to set up a rifle, and provide all the equipment for making the bullets. Most of the time I don't do it.
I just set up a older MK85 a couple weeks ago for a close friend. The new owner had never shot a ML in his life. He was hitting the center of the target at 50, 100 and 150 yards in about 10 bullets.
The technology is out there for accurate muzzleloaders. Even with all the technology in the world the owner still has to sight the gun in for how he shoots. He still has to clean it. And in the case for the way I set guns up, the shooter also has to make the bullets.
You said that the Purists are fine with the Status Quo. That is not entirely true. On some ML sites I am thought of as a demon that is ruining traditional muzzleloading. In others I am thought of as Daniel Boon.
I am neither. To be honest I have only a slight interest in the history of the sport. Mostly in the long range weapons and the technology. I only have interest in hunting with a rifle that performs like a rifle should. Hit's what it is aimed at, and is easy to maintain.
Plenty of guys want that too but there is no easy way to get it.