PM, you don't have any idea how much were these 'quite a few' in terms of per cent? About half? More than half? Of course, having a spare lock in your pocket does offer an advantage.

On the other hand, some novelties like ejectors, single triggers, etc., were caught on quickly, with every maker offering his variety. Quick detachable locks - there's only WR, then Holland's, and, for hunting guns, that seems to be all. The only place where they gained some popularity is high-end competition shotguns.

Russian Hunting Shotguns