Why do people not eat the rest of the rhubarb?

People typically avoid eating the leaves of rhubarb because they contain high levels of oxalic acid and anthraquinone glycosides, which can be toxic if consumed in large amounts. While the stalks are safe and delicious to eat, the leaves can cause symptoms such as nausea, vomiting, and even more severe health issues. Therefore, it is recommended to only consume the stalks and discard the leaves for safety.