I think the subtlety is that the phone itself is the infrastructure here - not the App Store.
If the devs can bypass payments for dev kits, then they legitimately are going to get a free ride; what do they think pays for iOS updates and the R&D for the new hardware that's needed for ever-increasingly-resource-hungry apps? If they expect the phone purchaser to pay that, they'll end up with far fewer target customers, because the cost of the devices would have to be vision-Pro like.
The other alternative is that the devs will have to pay up-front for the dev kits, instead of over time. Even if I was a mega-developer, I'd rather pay over time instead of all up front - time value of cash and all that.
So the argument really boils down to "mega devs just don't like paying and want more of the end-users money". I think they are playing a tough game of chicken with Apple here: if they reduce Apple's take too much, Apple's going to falter, so their customer base is going to falter, so in the long run they are going to be screwed.
I can't tell if Apple is looking at the longer term here either; it definitely seems like they are hell-bent on maintaining the status quo, public image be damned.
But until the mega-devs and Apple agree to cooperate instead of just challenge each other the long term prospect is poor.
I do have to say though that the fact that you get Epic's CEO being all belligerent and calling Apple "illegal" makes them sound petty - Apple has never publicly bad-mouthed anyone that I've seen in the news at least. They always use very carefully crafted language.