Agreed, Apple isn't going to say "Well since you asked nicely, I guess you can implement your own in-app purchase processing." But having an official recourse on their arbitrary app store bans from minor rule interpretations is still a great improvement. Probably driven by the antitrust attention they're getting, since otherwise they've been able to get away with whatever they want and small developers can't do anything about it.
The remaining big question is whether Apple will rule in someone's favor on their own, or if in practice the result is still "Things will get fixed if and only if they get enough attention on twitter."
- such created by accident weather it's because of suboptimal rules, vague formulation or reviewers give mad with power
- such created intentionally to control the platform in all reasonable and unreasonable ways
I believe Apple does try to fix or lesson the burden of the first for the benefit of everyone including them.
But they won't do so for the second reason where you most likely still get a no even if they are acting unreasonable.
At the same time they now can point to this and say "see we are all fair" even if they are not.