I also think it is better to open up slowly, cautiously, and carefully rather than start out wide open and then close up every time an existential threat appears on the horizon.
I recall when Etsy first put out an API. It was a read only API. Then they made it read/write. Over time they have added a lot of features that have made it possible for third parties to add value to Etsy and Etsy’s sellers and buyers. But they have always protected the essential things that make Etsy’s business and marketplace work and hang together as a sustainable entity.
Contrast that with Twitter which started out completely open which allowed anyone to build a third party client, grab a huge percentage of Twitter users, and then threaten to take them away from Twitter. That’s not a sustainable relationship between your product/service and the rest of the Internet.„