When they were the darling of corporate email they weren't interested in having outside developers.

Then when the iPhone came out they made a half-hearted effort to attract devs but there was no app store and to sign up you had to jump through the sort of hoops that a supplier of space shuttle avionics to Nasa would expect.

Then just when they had the sign up and an app store working they made an announcement something like - "it's all going to change with our wonderful new OS but we can't say at the moment how you will program it or if your old apps will be compatible" - at which point most devs looked at their market share and compared it with the number of customers on iPhone and Android and uninstalled the SDK.