"raising the taxes on the wealthy and then having to offset that with new taxes on the poor " That would not be Pareto efficient. If you raise the taxes on the wealthy they would be worse off. Pareto efficiency requires that no one be worse off. And, as you stated it, it appears that you are raising the taxes on the wealthy and also adding new taxes on the poor as well? So everyone would be worse off. Many economists would argue that a flat tax is not fair.

"that leaves all 100 taxpayer clades unhurt" In economics this is called Pareto efficiency. A change that makes at least one person better off and no one worse off. With complex systems it is notoriously hard to do. Undoubtedly the model proposed could create a better tax system, but nothing short of a miracle would be able to make the system better without making at least a few people worse off. Some of the cruft that would be cut out would hurt someone, and re-balancing another part of the tax system to compensate would affect more people than were originally affected by the cruft. Then you'd have to try and re-balance somewhere else, and that would affect people who weren't affected by either of the first two changes. The interconnectedness of complex systems makes Pareto efficiency fiendishly hard. To truly make the system better some people are going to feel pain. Trying to fix it without hurting anyone at all is like trying to live in the land of rainbows and unicorns. A very pretty dream.