I get your point, but looking at it at a glance without any other context, 12% feels like a pretty reasonable amount IMHO.
Like, if all major marketplaces only charge 12% from the get-go, we probably would have had much less fuss and lawsuits over this.
This issue was always the disproportionate size of the fee, not the fact that they charge a fee.
If Epic deserves a 12% cut of a Windows game sold through their store (despite not having paid the costs associated with developing and maintaining Windows) how large a cut should you get when you did incur the additional costs of creating and maintaining the platform?
How about making it 10%? As a modern-day "tithe".
I don't think a percentage makes any sense at all. Is it proportionately more expensive to host a $50 game than a $25 game? It's only a percentage Because They Can.