Personally, I think the truth lies in the middle. I think having full history for purchasing coffee is not only wasteful of space clogs the blockchain (imagine 6 billion people adding 3 coffees a day to the block chain over 50 years). My back account keep track of all transactions for a few years and I’ve rarely needed more, but I absolutely do need a transaction history for budgeting and taxes. So a hybrid approach where important or big ticket items have full transaction history (until you ask to prune to a MW), and smaller ticket items can be in smaller MW subaccounts of different categories is the best of all worlds.
Actually both since it is an important way to avoid and resolve payment disputes. Private ledgers mean nothing in a payment dispute. It’s so important that without it, for large payments everyone will have to involve a “trusted third party” to keep everyone honest. It’s the reason why good cashiers never put payments in the cash register until the customer leaves…without this “trick” it’s easy to be scammed. It’s the whole reason double entry accounting exists. MW also doesn’t completely fix the issue of exploding blockchains. With 6 billion people on MW (arbitrarily chosen number) and each person having multiple wallets and wallets being lost and new people coming into MW regularly due to new births the number of wallets will explode. There needs to be a regularly get rid of abandoned and locked out wallets. Hard forks like Seraphis are a good way to find out who still has a wallet and eventually clear out the old wallets, but you can’t keep doing that for a stable money supply. I’ve stated before, I fully support transaction fees being partially based on how big your blockchain footprint is as long as you can “close the books” and compact your footprint. I’m also open to fair schemes dropping abandoned wallets (e.g. calculate a “fee” based on blockchain footprint and time of last access. If the “fee” is less than the amount in the wallet, then do nothing. If it is greater than the amount, then the wallet can be pruned.).