Along the same lines as this thread are the parents who allow children (older) to use the pool use late at night at the resorts when those children are making loud noise.
There's nothing wrong with an after dinner swim, however when it's 8:00+ at night and they are screaming and shrieking at the pool and playing like it's 2:00 in the afternoon is incredibly intrusive.
Most of the same reasoning applies: people have paid for the resort rooms and don't enjoy hearing screaming *children* ('tweens, etc.) while they are trying to relax.
I think what we're all after is some common courtesy, be it at the restaurants and the pool.
HOWEVER, I think we should ALL try to look at every situation with at least some sympathy and understanding and giving of the benefit. Life is too short.