Why were ships-of-the line not supposed to open fire on frigates during fleet?

Ships-of-the-line were big, strong ships that fought together in a group, and frigates were smaller, faster ships that could zoom around them like kids on bikes.

Ships-of-the-line were like the tall kids in class, they stood out and could take a punch without flinching. Frigates were more like the quick runners who could dart between desks and grab your pencil before you knew it.

During a big fight at sea, all the ships would line up and battle together, like a team playing a game of tag. If a ship-of-the-line opened fire on a frigate while they were still in formation, it was like the tall kid suddenly threw a ball at the quick runner, it might not look fair, and it could mess up the whole team's plan.

Also, frigates were tricky to hit because they moved quickly. If you tried to shoot them when they weren’t ready, you might miss or waste your energy on something that would just run away.

So, ships-of-the-line saved their power for when everyone was fighting together, it made the whole team stronger!