I build a product that pre-dated App Center by several months. Facebook dev relations people tested it and actively encouraged me to build it. I was assured that it was considered "good" and "helpful" as an example of using Open Graph. At an earlier point I was offered marketing help from Facebook for my launch.
I am not clear why some folks don't see the issue with building something that is encouraged by employees of a company, and then, in the matter of months, being told "never mind". That is not good for an ecosystem.