Imagine an alternate universe where the Steam client had feature parity with our universe's Epic client, and Epic's client had feature parity with our universe's Steam client. Do you think users would abandon their Steam libraries for the Epic Store, in order to have home streaming?
What's relevant to this discussion isn't what features you like about Steam, but what features cause people to make Steam accounts. In other words, is it actually possible for another player to compete on features alone?
You can use both steam and epic simultaneously, there is no need to abandon anything. In your proposed universe I most definitely would be making new purchases on epic wherever possible.
Exclusives of any kind are anti-consumer, whether it is steam doing it or epic.
What's relevant to this discussion isn't what features you like about Steam, but what features cause people to make Steam accounts. In other words, is it actually possible for another player to compete on features alone?