From his posts on Genshin it is clear that he is a genuine RPG player, so the mindless content is irrelevant so long as there is the challenge to perfect your squad. He will tire of it once he's mastered the mechanics and the content doesn't refresh fast enough to overcome the diminishing returns of maxing out another character. Your point was most valid in that he was clearly a passionate spokesperson for Gwent . From his exit piece up on YouTube, where he did cite the content issue, he also expressed a frustration with his gameplay. When a seasoned player feels that certain match ups are beyond countering, it is time for the development team to take note. I can certainly relate to this viewpoint as Lockdown + Mill or Lockdown + Clogging has become a game of simply playing out cards, or conceding upfront to save time. Who wants to waste 10 minutes on an inevitable outcome. Yes, I have won over both decks, but 9/10 my game was disrupted beyond repair. Without lockdown, the odds are at least even, and my choices matter to the outcome. There are multiple strategies built into my favorite NR deck, but it can't overcome the combo of disruption plus strong finishers that require a lock or final say with yrden.McBeard isn't just a steamer though, he's also a castor. Meaning he's on the game's payroll. So when someone like that comes out and says he's lost all interest in Gwent, it's kind of a big deal in terms of the games image.
His main complaint is that Gwent doesn't have a clear roadmap like its more popular competitors (Legends of Runeterra and MTG). It's hard to have faith in the game's future when CDPR apparently has nothing planned ahead.
It's not like McBeard leaving is something new though. All of Gwent's biggest content creators left the game a long time ago.
MisterHabbla also has recently addressed this situation, and I would not be surprised if he looses interest as well. I hope the development team finds a way to limit this prevailing feeling that the better players are not winning. Lockdown never deserves a GG.