In this case, it’s conditional. Even assuming the tree is dead it could be a reasonable anchor, but it depends on a couple of factors. First, what loads is the anchor going to see? On TR, you usually don’t have the risk of a high-force fall, but if the route has significant overhang or traverses, you need to be more careful. Second is how strong is the tree/root? In this case, I probably would attach myself to a better anchor uphill and then yank on the trunk and roots to test how solid they are. Tree type also matters - from the little bits of bark & green, I’m guessing this is a cypress of some kind, and they’re very rot-resistant. OTOH if it were something like a birch or a pine I’d be a more hesitant to trust the dead wood.
Putting the third leg of the anchor into rock is a good insurance policy on top of that.
IMO there’s something about the style of vote-moderated public posting that leads people to want to posture as confident and authoritative, even when they don’t have a lot to add. And cynicism is a cheap way of looking smart (since it undercuts the need to deal with complexity and nuance). So there’s a constant bias towards posting cynicism or framing ideas cynically.
On the flip side, shorter comments are easier to read, and sarcastic/cynical retorts/summaries are more likely to get upvoted when they’re shorter/funnier than effortposts. So there’s also maybe a bias to upvote cynicism.