The facilitation is of value to both consumer and producer. Why should they extract value from one and not the other? Or, to put it another way, if their facilitation for the producer involves more work than it does on another storefront, why can't they ask for more value than that other storefront? I would suggest it would take a lot more effort and expenditure to be able to even technically reach mobile customers, without an facilitator like Apple or Google, than it would take to technically reach a PC customer without Valve. It's true that beyond technicalities, Valve has a built-in market that it offers access to, and it should be rewarded for that value, but because they don't engage in all the heaviest parts of the chain to reach a customer, their position is easier to dis-intermediate and disrupt than those gatekeepers who do engage in all the heavy lifting across a chain from producer to consumer. I just don't see why the value in managing the whole path from producer to consumer shouldn't be credited to them in the storefront cut.