Is this 2004?
If Valve had no real competition they would tell publishers to fuck off. It is just selling games after all, it isn't rocket science or isn't something the other publishers couldn't do by themselves.
Which they do, which they do a shit job of. Steam is fine and the quicker services like Uplay die the better we will be.
If it was just selling games users wouldn't care where they buy them. From GOG to Steam process of buying games is same, put item in cart, click checkout, pay, enjoy. But because users care about service they complain. And no Steam being only DD service is really not good idea, monopoly is never good idea no matter how good company behind it is.