I did this for a friend...who has a stereo in his car that costs 8x a gaming rig, till I eventually gave up and handed the account to my brother in law I was recently living with.
You know what I realized?
NOBODY uses anything except Steam
I don't think there are more than a handful of users who actually play these freebies before they become free elsewhere for Steam as well, me being one.
If Epic upped its game and gave away a free RPG or something like Origins Of Final Fantasy, NFS Unbound, Creed Mirage, or something hot off the block before everyone and their cousin who had any interest in it had already played it or owned it elsewhere, it may have did them some good.
As it stands right now, they're just giving titles away for nothing constantly instead of giving away a few grand titles that may have got people adjusting to their launcher and even forced some hardware upgrades on them (like a new controller) just to play that $50 or $120 game because it was cheaper to buy a new gamepad than to purchase it on Steam.
I'm sure eventually they cross a title that will make someone deal with it temporarily, but nothing like you would if you were going to dump 400+hrs into a game and you knew it.
I have more temptation to use Origin and I own a whole of like 10 games, all of them free, except a few NFS titles