In my old age (29) I don't think I will ever understand streamers or why people care what they do. Just from the thumbnail is he switching to Genshin Impact? Now that's quite a brainless game.
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.