There's a sample bias - People are likely to try appeasement when they are powerless, which makes appeasement unlikely to work.
It's also the kind of thing that gets forgotten when it works but remembered forever when it fails. See Appeasement in international politics.
This is our monthly thread for collecting these little gems and pearls of wisdom, rationality-related quotes you've seen recently, or had stored in your quotesfile for ages, and which might be handy to link to in one of our discussions.