Responsa for Menachot 79:3

אמר רבי א"כ למה אסרוה לפי שאין בקיאין

Rabbi said, If that is so, why did they forbid it?<span class="x" onmousemove="('comment',' Since it is not forbidden in law, why did Beth Shammai impose the restriction? Aliter: since Beth Hillel's view was accepted as the law, why should it create amazement in Jerusalem?');">⁴</span> Because people are not versed in the law.<span class="x" onmousemove="('comment',' And if it were permitted to wear diverse kinds in pursuance of the precept of zizith people might forget about the precept and would wear diverse kinds in all circumstances.');">⁵</span>

Teshuvot Maharam