I'm surprised LCD doesn't get done for dummy throws sometimes. I think it's because he does it not from a pump but lifting the ball to throw. Similar to "I'm just peeking not dummying" by scrum halves.
Sinkler and Genge were part of the age of let's get props who can get around the field like a flanker, tip on and distribute. Scrummaging was secondary. It sort of worked for a time until they came up against their antithesis.