On a multi-story house, some section of the upper gutters do not have a
direct connection to the ground level storm drain, but instead dump its
water onto the lower level roof, which eventually reach another gutter that
drains to the storm drain.

Why do I need this type of gutter? Without it, the water would run off the
upper roof and drop down to the lower roof anyway.

I'm trying to see if I can reduce the amount of gutters on my house to ease
cleaning and to reduce cost should I replace them with new and better
gutters.