In my opinion, a great place to define that boundary is when you have to move to a completely separate app; unless something's majorly changed recently, you can't access the majority of Facebook or Instagram from the other app unless you end up in a WebView and login that way. At that point, you aren't using a native experience where they have the same level of access that they do from the actual app and the main issue about having the camera open isn't even relevant anymore, haha.

That isn't to say that Facebook Inc. (the parent company) doesn't have their hands in the Instagram pot, because they obviously do and it only seems natural based on their past behavior they'll integrate heavily and push way past bounds they should be allowed to. All of that said, it doesn't mean the other poster is wrong about making it known this is a problem inside of Instagram rather than in Messenger or Facebook (the app).

I understand where you're coming from; being able to deflect their transgressions on a child company and then toss it aside and rebrand when it gets too much heat isn't a way they should be able to operate; heck, I'm just as skeptical as anyone that this is just a "bug" and have personally disliked FB's practices for a while; however, it doesn't make sense to start treating all products from large companies as if they're all just one single thing. In my mind, I akin it to Google having a pretty gnarly bug in GMail, but then everyone not being able to separate it from Search; it feels like an apt comparison to me, especially since Google is just a few steps down from the nefariousness of FB in some people's minds.