cashu is not bitcoin. It just uses bitcoin as a starting point. zapping with cashu and using it as money will reduce the frequency and circulation of buying and selling using bitcoin  - it may not be visible now but but when there are many "add fancy  privacy related name" token coming in, or high usage of tokens, it will drastically impact circulation of bitcoin and its chances of becoming global currency. This is exactly how altcoin comes into bitcoin. This is not a good thing.