So it's now anticompetitive to want to be paid for providing services? They aren't going to deny developers for selling the games outside the sandbox, they are going to deny developers the use of their distribution platform for sales made outside the service.

A real world analogy: you can buy Levi jeans at Walmart and you can buy them on Levi's website. What some developers are doing is the same as Levi selling you a pair of jeans on their website then saying "pick them up at your local Walmart at no extra cost". Even if Levi replaced Walmart's jean inventory, Walmart is losing sales while having to pay for the store and employees to process these walk in no money transactions.

Valve should not be expected to handle server and bandwidth costs for sales that don't go through their platform. The percentage they take off transactions through Steam are to pay for these services much like Walmart takes a cut of sales to pay for their expenses. Levi is more than welcome to open a store right next to Walmart and sell jeans at a discount to compete as then they'll be paying their own store and staff expenses. A developer is welcome to sell their own game on their website but do it via a direct download (where the developer pays for servers and bandwidth). They should NOT be selling Steam keys where Valve gets no cut but is expected to provide the download service.