To make double spending an impossibility. ACH holds the funds until both parties agree to the transfer, then it clears.
Checks are instructions to banks to do exchange funds on your behalf.
Exactly. And most of the world haven't used them for years. This is quite weird that Americans still do. But then again: magnetic stripe cards, slow adoption of contactless payments, no instant electronic transfer... you're very traditional.
Many countries in the world are already preparing for cashless reality.
I'm not surprised at all that Japan is the first country with solid bitcoin regulation. They were always leading the electronic payment innovation and implementation.
Reasons not to blockchain:
-computational cost is astronomical
It doesn't have to be. Current cryptocurrencies are designed this way, but it's not a must.
-nodes can still exploit the network fabricating debts for illgotten profit
What exactly do you mean?
-there's no authority to fix a problem. Case in point, if a vulnerability is discovered in Bitcoin's hashing algorithms, the entire chain will come crashing down.
Again, this is stemming from how bitcoin is designed. A closed, bank-run blockchain doesn't have such issues. Only the bank will do hashing.
-Bitcoin only handles maybe a quarter million transactions per day: a country like the USA has billions which translates into astronomical costs. Centralization means conservation of resources--no more redundancy in the system than is necessary.
-Looking at the statistics, it almost appears that doing more than a quarter million transactions per day is impossible because of the amount of overhead required to accomplish it.
But you're talking about issues of Bitcoin, not blockchain in general.
This can be all addressed by a more specialized, well-designed blockchain solution.
Also keep in mind that even without blockchain the financial system is very demanding computation-wise. Blockchain is not going to be an addition. It will replace some currentlu used technologies.
On the other hand, we have to remember, frankly, banking technology hasn't evolved much during the last decade.
Compare today to the pre-crisis times in 2007. There are not many more humans (+15%) and they have similar financial needs. The number of traded stocks and other financial instruments didn't grow either. The instruments are not getting more complicated and 10 years ago we already had things like high speed algorithmic trading.
So what has changed? The computers did: they're 20-30 times faster.
Also don't worry about profitability of this idea. People mining at home are often not rational. They can't forecast properly, they can't estimate risk - financial institutions can.