In addition to competition, there were also safety issues with proprietary chargers. I personally experienced this, when I had an emergency and my LG Lotus was dead. I tried using a borrowed microUSB charger at the hospital, only to be presented with the message, "Please use an LG-branded charger."

The power rating was identical; but, they had some kind of crazy, DRM-like scheme in place.

I'm very glad that I can now use or buy a cable anywhere and use pretty much any block, even an inefficient one.