That makes no sense, the browser is sandboxed significantly more than any native app. Please stop assuming everything Facebook does is out to personally attack you or your data. It's demonstrably not the case.
Seems to me that you're making a blanket statement, here, that is contradicted by most of the available facts. How about some support?
Personally, I'd say you'd have to be an idiot to NOT assume that a large number of Facebook's actions are not intended to get more access to more kinds of user data. We've got about a half-decade of proof of this.
They just added very easy to understand privacy controls, for one. They're good enough that I'm considering merging my two "identities" into one Facebook account rather than my current two: I can now easily keep them separate.
The other point is that it's impossible to prove the negative. Any action can find an interpretation that it's an assault on privacy — if that's the interperetation that helps make your point — but it's difficult if not impossible to prove there was no malicious intent by anyone related to Facebook.
At least I, for one, find it hard to believe that Facebook really cares that much. But if you want to believe they are out to get you, I'm sure you can find and twist whatever you want to suit that opinion.