You're right that it uses itself as a prototype for decisions but the fact that it also maintains a probability distribution over possible hole cards and that it updates according to observed actions is already richer than the local decision only approach taking most all other bots. This is sort of forced by the simplicity of poker's action space combined with the large search space and imperfect information. Here, the simplicity ends up making things more difficult! They also use multiple play styles as "continuation strategies" so it's a bit more robust. And to be fair, I suspect much of human play does use themselves and experience as a substitute too.