Being stuck in someone’s guard can be a dangerous position, as this is the most offensive and defensive position the bottom player can have. Arm bars, triangle chokes, omoplatas, Kimuras, and more are available to them there. At the very least, your offense will be muted against a good guard player.
This is why we usually want to pass the guard. When we go into a dominant position, such as side control, mount, or back mount, we take away most of their offensive and defensive capabilities, and enhance ours. One of my favorite guard passes is the Double Stack, which will fold your opponent in half and make them hope you pass guard quickly.