"Your friends will only be able to sign up using your link if they never played GWENT before. "
Thats is pure stupidity right there CDPR, all my friends alredy tried Gwent when it was in Beta, nearly all of them gave it up when HC was launched, and now I can't even use this invite program to try to get them to give the game another try? WTF were you thinking?
You need to get rid of this requirement ASAP and allow people to use the invite incentives by simply linking up with other friends on their friend list, even when they already tried Gwent before.
When you are trying to get people to give Gwent another try after the HC 'brilliance' how can you make such a boneheaded move as to not allow existing players that still stick with your game to use this program to get their old Gwent friends to give the game another try after the failed HC update that you are still fixing up and still lacks key features like seasonal trees, reward trees, trinket descriptions, etc...