Well I’m 62 years old and provided I use magnification painting 6mm ant a problem.  The whole “I can’t see them let alone paint them” just doesn’t wash.  The bottom line is usually cash, magazines will promote those who pay their wages.  That plus the the inertia of always having used larger scales means 6mm has to work twice as hard to get the message out.  It’s not like 6mm or 1/300 is a new kid on the block.  I first became interested in the small scale figures back in the mid 1970s when I first saw Heroics and Ros Macedonian Pike blocks and micro armour.  We have been around longer than 28mm and at least as long as 15mm.