It's not even that they say it's been ineffective; they're saying that the EC can't prove that it has been effective.
And AFAIK there's also no reasoning given why it's fine to prevent apps from mentioning other payment options, even assuming it's not anti-competitive. (But to be fair, I haven't actually gone to the source to read their statement.)
No, if Apple tries to give advantages to its own music app it is still possible for their app to fail if it is bad enough compared to the competition even if Apple gave themselves large unfair advantages.
In cases where Apple succeeded in killing the competition you wouldn't see a lawsuit like this since the competition wouldn't have the money to sue properly.
This isn’t a lawsuit and it’s not being brought on by competition so I’m not sure why any of that is useful to say.
I did not say it’s impossible to be anti-competitive without being effective. I just said it’s a factor when judging whether something is. So your first point is irrelevant as well.
And AFAIK there's also no reasoning given why it's fine to prevent apps from mentioning other payment options, even assuming it's not anti-competitive. (But to be fair, I haven't actually gone to the source to read their statement.)