Don't know about Epic, but Steam & GOG don't really invade your privacy.  They only collect stats on your gameplay.

The devs will answer the rest with certainty, but I guess that, at some point, you will be able to buy the game through Stardock's store, at which point maybe it won't go through a 3rd party.

Epic allows offline play also

Probably not. It's just not viable for developers to maintain independent downloaders, managers and various apparatus to handle payment processing etc.

It should be noted right now on EGS you can launch the game without launching the EGS client. But you do still need the client to download the game and update. The same is true of our games on Steam and even GOG has its limitations.

This is just the way games are sold and distributed these days.

Gone are the days of "standalone" games that are launched without loaders ... it has been over 10 years since I purchased my last cd/dvd game and even then I didn't need a cd/dvd drive as they gave me a steam key to download the game! 

If you use a web browser such as IE, Chrome, Edge (how do you visit this forum?) they are also collecting all specs of your machine.

I'm sure your "privacy" concerns are valid but i'm sure most people have better things to do than to analyse the amount or type of memory you have on your PC, or the screen resolution you run at !