They are a problem because they are metal. They go up under the shingles (if that is done correctly), so when ice and water are up there in the winter, it hits the cold metal, freezes, and can creep up under the shingles. They cause major ice dams. The other problem is that they have a gap/hole/slice for the water to drip in, right….There are things smaller than a usual leaf that is in the animation they play….pine needles, dirt, etc. Now, how do you get this one piece metal off and clean out your gutter when it clogs?
The advertising for it is pure BS. You can’t say that you’ll NEVER have to clean your gutters. Just a stupid thing to say, IMO.