While multi-agent discussion has been proposed as a promising strategy for improving AI reasoning capabilities, this paper finds that discussion can be more detrimental than helpful. While previous research has focused on discussion within homogeneous agent groups, this study explores the impact of model power diversity on the dynamics and outcomes of multi-agent interactions. A series of experiments demonstrate that discussion can decrease accuracy over time, even in environments where stronger models outnumber weaker models. Analysis reveals that models favor consensus over challenge on incorrect inferences and frequently switch from correct to incorrect answers based on peers' reasoning. Additional experiments explore various factors contributing to this detrimental shift, including flattery, social conformity, and model and task type. These results highlight a critical failure mode in reason exchange during multi-agent discussion, suggesting that simply applying discussion can lead to performance degradation if the model lacks the ability to encourage discussion or resist incorrect inferences.