It's very simple, this is about the threat model.

If you are worried about big players profiling you (hard to avoid, high likelihood of happening, low likelihood of damage), then you want Sailfish.

If you are worried about apps profiling you (easy to avoid, high likelihood of happening, moderate likelihood of damage), you want Android or iOS.

Graphene and Sailfish sit on different points on that spectrum, just like OpenBSD and Linux do.