>>714574458 (OP)Steam isn't different from a physical store in the sense that they charge a markup. That criticism is weak, IMO, because that's just how retail works. Most publishers don't want to sell their games directly because it means they have to provide additional infrastructure that increases operating risk and costs money. They outsource that to retail, pay for it, and are done. The publishers who aren't okay with this or can afford to do it in-house have created their own platforms, though they're not as successful.
And this does indeed lead us to the valid point of criticism: Steam is basically a monopoly. There are cases where monopolies make sense, but video game retailing isn't one of them. But then, we also have to admit that the platforms that competitors offer are just flatout terrible compared to Steam and Valve isn't actively pursuing devious tactics to oust competitors from the market via buyouts, supplier control, etc. - as far as I know. They're even more expensive than other retail platforms, no?