I totally agree... my point was that designing something as a hobbyist then taking it to market is a different ball game to an experienced designer designing for mass production and manufacturing tolerances etc.

One of the key differences is testing. As a 'hobby designer' I'd consider ten or so prototypes tested by friends (or worse, the first dozen or so unlucky punters - were you one of those I wonder) as adequate. As a manufacturer I'd want to build, and evaluate to destruction if need be, several hundred at least before letting them loose...