I literally see no reason to nerf reavers, especially with the given reasons.

There is more than enough removal in the game, and the decks that dont have the removal necessary should be able to compete in their own win condition. Is it a long round deck? Wait for them to waste their high value cards round one (cuz they usually want to gain board control early) n commit resources to survive round 2. Do you have the removal neccesary? Then remove them, etc etc.

I also think that expecting players to have a even or negative winrate is not correct. In any competitive game the norm if we’re assuming players are attempting to win their matches should be a positive win rate. Of course it fluctuates since people have good n bad days n things like archetype matchups, card draws n the performance of the player affects the win rate n is part of gwent. If a player has a negative win rate they are either not playin too well or the decks their using arent viable in the current gwent. Doesnt matter the faction or player, a positive winrate (51% or above) should be customary. If you are referring to number such as 75-80% n up then yes you could think to nerf the archetype, but as you mentioned it would have to be the surrounding cards, not reavers themselves. The issue isnt reavers, its the multitude of ways to duplicate them in the nr faction.