Why is it that the chunky spring loaded rear sight, screwed into the barrel, is the default on modern production traditional muzzleloaders and muzzleloader barrels? This sight design is not traditional, and seems more expensive and less robust than a rear sight with an elevator, like the Marbles #63/#67. I really haven't seen the spring loaded sight design except for on airguns, and I'm curious of the history on how it became ubiquitous on muzzleloaders.
"Default" sight:
Marbles #63:
"Default" sight:
Marbles #63: