Honestly that's just cruel to say. It doesn't take a lot of effort, and does the receiver no good. Worse, the receiver who you intend this comment for won't even read it, so it appears purely performative. If they are smart, they'll puzzle that out on their own, and if they're not, they'll just take offense if they heard it from a stranger.

Besides, the land is advertised for building castles on. People have built castles on it before and there are people with some big castles on it right now. It's not an unreasonable move to see that and try and participate.