It probably has to do with warranties. When you DIY, a failure in a year is an opportunity to do the latest thing. When you sell with a 3-year warranty it's an existential threat.I have a feeling it will become clear and a better market soon, once a few companies have a nice cob light out. I really can't believe its taking so long...amazing given the need
The average LED buyer isn't that discriminating. Many are taken in by pretty web pages and outrageous claims. If a typical seller upgraded to COB they'd be incurring a risk (unproven reliability) their competition hasn't, only to sell to a very small discriminating segment of the market.
It's the "Crossing the Chasm" syndrome. The bell curve between early adopters of a technology and mass market.