By marginally "free" I mean like cable TV - it doesn't cost much at all to enable some channels for a customer, even though you charge them $79.99.
But something that costs $50 to provide, sold for $80+, there's no margin there even though it appears there is.
Grocery stores have tried the "meal in a box" and failed; and they're best positioned for it.
But yeah, the margins are brutal. And the market is a sliver: people willing to cook but not wanting to do all of the research and shopping. I've never had the service because I actually enjoy cooking and even shopping for groceries. But I've helped other prepare their Blue Apron deliveries, and I really enjoy it.
So I hope that the business model doesn't get completely squeezed out, even though I'll never use it.