Apple is focused (theoretically) on privacy now, but that doesn't mean they won't change, and if they do change, Apple users won't know about it until their information is sold.
(a) it’s not really theoretical, considering both their public stance on it and the design choices that they’ve made; (b) “but they might change” is a bugaboo that could apply to anyone. An open source project could get compromised, taken over or bought by a malvertiser who replaces the software with a signed malware - and we have ample evidence that this has happened before to many projects (e.g. Chrome addons).
