Some care about tradition, some don't.
This gimmick doesn't do anything a normal cap can't do. It just slows down the reloading process and takes money away from the unwary. Crap like this has been around since the rebirth of interest in muzzleloading in the mid-fifties. And it always finds buyers--among the least traditional shooters whose commitment to doing things as they were done is limited. People not quite sure of themselves and their guns. People looking for an edge. People with no commitment to history. People looking for an easier way. People who would be better off with a scoped, stainless steel, plastic stocked, sabot shooting, smokeless powder burning in-line rifle. Instead of pretending and modifying a traditional rifle one bit at a time why not admit that the sidelock guns aren't your cup of tea? :v