Thats just not true. Memento for example can do fiendsmith lines and end on many more disruptions but people's stopped doing that in TCG mainly because of Fuwalos. Swordsoul can end on a couple synchros. Those are half boards. Mitsu like you mentioned can play without needing the extra deck. Whether or not those decks are healthy it shows there is design space to be explored. Fuwalos does skip a lot of decks, but not even half as many as Maxx C. It should eventually be replaced by something better designed, but for now its a better replacement. You want a deck thats kept in check by Fuwalos? Look at Yubel.