If you look at how people act in work, family and love life, signalling explains 90% of it.
Hanson became interested in signalling because his work in prediction markets. Prediction market well implemented seems to work and produce good actionable information. Companies were eager to adopt them. In practice they are catastrophe because they reveal how the choices being made are based on other things than what is said. The whole social structure in workplace is destroyed if the positions and knowledge people signal is revealed to be not true.
But it equally explains why I don't buy a car (because I want to signal that I'm not the sort of person who would) as much as explains why I do by a car (ditto). So of course it "explains" 90% of how people behave, but only after the fact. Which is suspicious.
But the commenter points out that most charity is in practice anonymous, which is a serious challenge to any framework that presupposes one's actions are publicly know by others.
It's like the creators of this theory only consider the charity of celebrities, which indeed do it mostly for signalling, and forgot the vast majority of humanity that doesn't get their actions described in the papers...