Jarhead is 100% correct. "If the experience is better than what Steam offers" - well it's not even close, with any client, and some of them have had years and haven't been hobbled by the same ridiculous kind of "flat management" style Valve apparently uses either.
Valve have said in the past that the cut they ask for is necessary in order to fund the development they do on Steam. Without being privy to their accounting records, it's hard to argue otherwise.
It's easy to lose sight of just how much work Valve put into Steam. And not just Steam either - Windows-only people will not realise it, but Valve contribute shitloads to the free software community as well. Like, a TON. Read about Proton, for just one example.