A small number of angry customers can cause a disproportionate amount of harm to a company through bad-mouthing to family and friends over an extended period of time. It can take years to earn customer loyalty, but only a day to lose it.

However, the actual size of the DIY programmable remote market probably isn't the issue. If the DIY market was really big, Philips wouldn't want to give it up. And if it was so small, Philips wouldn't have bothered to make a policy change at all. The only explanation that makes sense to me is that custom installers complained to Pronto Team about DIY-ers costing them lost (theoretical) programming services revenue, so Pronto Team is just trying to please the installers, as well as keep an air of exclusivity about its products so it can maintain favorable pricing.