No, that can be done without a blockchain. The only piece you need is digital signature, an established technology. If someone hands you a block of data with a signature, you can hash it and check the signature corresponds to the purported signer.
> As for value, consider that even for legal businesses in many countries even getting bank accounts...
Yes, because there is such a thing as money laundering laws. I have a friend who is a specialist lawyer in this area, and it's actually non trivial to do KYC, especially for people from certain countries. The procedures and various banks' understanding varies as well, hence your issues. And this is an important point. If there were no restrictions (who can have an account, and what do they have to disclose), there wouldn't be much of a point in bitcoin. Everyone would just find some old bank somewhere that would give them a numbered account, and that would be that.
That's entirely insufficient, as it doesn't prove that the chain you have been given is genuine. It just proves that each transaction is signed by someone holding the right signature. Nothing in your scheme prevents multiple diverging chains. The entire point of the confirmations etc. used by blockchains is that not only each individual transaction can be verified as coming from a specific source, but that the chain as a whole can be verified to meet certain criteria - specifically in the case of e.g. Bitcoin, the criteria that it represents the view of the majority of the mining power of the network.
> Yes, because there is such a thing as money laundering laws.
That's just a small part of it. Providing sufficient information to satisfy that part is the easy part in my experience. I'm sure that would be different in some countries. If it was just about money laundering laws, it wouldn't generally be a problem.
But in my experience the much larger issue is that many banks and payment processors have a lot of policies about what kind of (legal) businesses they want to be involved with, because being an intermediary means they take on risks - whether monery or PR related - and that makes them hard to deal with if you're a small company without tons of cash, and they're not going to tell you quickly in most cases, because they are perfectly happy to bend all kinds of rules and principles if you can convince them there's enough money in it.
In the cases I've dealt with, KYC has never been the issue that has caused delays. The legal hurdles have been cleared in no-time. The issues have been over perceived business risk. And that's fair enough - these companies are businesses too and need to safeguard their own business.
> If there were no restrictions (who can have an account, and what do they have to disclose), there wouldn't be much of a point in bitcoin.
Everyone can have an account. Finding someplace to get an account is trivial if you have nefarious purposes in mind. Heck, with enough money (around $500k last I checked, probably higher now) you can get a fully legally registered bank in a suitably off-shory location, complete with nominee directors and the ability to do your own wire-settlement.
The issue is the hassle involved with getting business banking accounts and associated merchant accounts and a payment processor to service it in a developed country, without lots of waiting or paying truly extortionate rates.
No, this is wrong. I can sign a chain of transactions (Merkle tree is used in BTC as well), and you will know it came from me. If I'm a central authority, I can keep signing it in all of perpetuity, and it will be verifiably from me. As long as you trust the signer, it's very simple.
The reason Bitcoin is different is because you want to be able to have different signers doing each block. The way bitcoin does it is through clever incentives: miners only believe that other miners care about the longest chain, and they want to sign that last block because then the other miners will recognise their mined coins.
As for value, consider that even for legal businesses in many countries even getting bank accounts set up is a massive pain, and being able to take online payments even more so. It can be a distraction from anything from days to weeks or even months. In two different companies I've worked on billing we ended up having to implement multiple payment processor backends because we needed to be ready ASAP after getting approval, and so started one integration only to get rejected, started another, and so on. Months of aggregate developer time wasted because there was no immediate way of guaranteeing we'd be able to take payment via a specific provider. It's getting better, but slowly.
International wire transfers is another "fun" one, which is usually slow, expensive or both, and with lots of arbitrary limitations (e.g. I once had my old bank refuse to transfer funds directly to a customer of a specific Russian bank - this was not during a period of any kind of sanctions; instead I had to wire to an account held by the Russian bank in a US bank, with instructions to move the funds on to the recipient account). My Norwegian bank at the time had no objections to facilitating that transfer, knowing full well that the funds would still end up the same place, but it did mean I had to waste extra time getting the recipient to talk to his bank to figure out the "workaround" and then going back to my bank with the details.
There is significant amount of friction in traditional banking, and even providing tools for mitigating that (or forcing the banks into fixing that to compete) would provide huge value. Maybe the downsides will continue to outweigh the possible benefits, maybe not.
> Even if you decide to go blockchain, you will have to meet with the other banks to make sure everyone agrees so they'll want to be on the same chain.
A big difference is that you can opt to bypass the bank for a number of services. Many won't want to, but for others it provides more flexibility in e.g. picking software vendors over a bank intermediary, or creating custom solutions.
(And yes, that leaves plenty of opportunities for people to lose money by doing it wrong too - we have years to go before we'll see what the fallout is and which areas this works well enough)