The authors of the book titled "Secure Multiparty Computation and Secret Sharing" claim that there exist functions which cannot be computed with passive perfect security for $t \geq n/2$ corrupt parties, where $n$ is the total number of parties. The authors prove this by showing that no protocol $\pi$ exists for secure 2 party AND with one corrupt party. However, for a 2 party protocol ($n=2$), the threshold of 1 can be written as a function of $n$ as $n/2$ or $(n-1)$, since $n=2$. So how can we guarantee that $n/2$ is the optimal corruption bound?
Can someone please help fill the gap in my understanding?