A fine isn't even necessary: Apple's App Store business just ended. Between app sales and IAP it has a 30% tax. If an app developer swaps out for a Stripe portal they're paying 3% and probably at least doubling their own profit margin.
Only an idiot would still be selling apps through Apple's payments next week. The only way Apple will make any money at all on apps is if it drops it's fees to 10% or below.
A fine is still necessary because (as per the original ruling), they should have never foisted their store on people seventeen years ago when they first launched it and certainly should not have done so when the court ordered them to stop four years ago.
If there isn't a fine, the message will be that it's fine to profit off of ignoring court orders until you face thread of contempt charges.
If the terms were so great and the value to developers so high, it should definitely have been able to succeed in a competitive market, and need not have been forced on people.
I think most of the praise was because before the App Store, you quite literally could not install software on iOS. If the Mac worked the same way, people would absent-mindedly praise Apple for it too.
Only an idiot would still be selling apps through Apple's payments next week. The only way Apple will make any money at all on apps is if it drops it's fees to 10% or below.