Valve are getting 20-30% of every sale. Other marketplaces - notably Google and Apple - are rightfully despised for this level of rent seeking

The contention is that you're using Epic's dishonest framing of this argument. Retail fees are not rent seeking, and the only "despising" of Google and Apple came from Epic themselves because they did not want to get any less than all of their MTX money from Fortnite on mobile.

The 30% cut is the standard retail fee. It's the standard for all storefronts except for two: EGS and Microsoft.