IMO the baseline for comparing is an air pad, ground cloth, quilt, and tarp [using your hiking poles or a ridge line for the tarp]. Since an UQ is heavier than an air pad and a hammock is heavier than a groundcloth, a hammock set-up is always going to have a slight weight penalty.
But comparing the hammock and tarp to a 1P double wall free standing tent might be a more fair comparsion for most people.
I accept the weight penalty when I use my bridge hammock because of the comfort and site selection. In the forests of New England, a hammock allows me to camp in places that you couldn't use a tent.