What the article gets right
The article is quite right to point out that ledger based on blockchain doesn't actually solve things people have problem with. For example, a ledger based on private blockchain is really nothing more than a poor substitute for technologies the banks already have. Public blockchains like Bitcoin is a bit more interesting but I agree that it is unlikely to "change the world", at least alone.
What the article gets wrong
The article doesn't address Smart Contracts, which is much more interesting than boring ledgers. The biggest difference is that we don't have anything like it right now. The ledger is boring because we already have ledgers. Smart Contracts are interesting because we don't have anything quite like it now.
Smart Contracts' little brother did change the world
Before we talk about Smart Contract we should talk about APIs, because in my opinion Smart Contracts are essentially APIs on steroids. So what's API and how did it change the world? API itself is as ancient as programming languages. But we came to understand its true importance only recently: the ability to package services into building blocks and combining them to create new services. Amazon is a famous pioneer in this, who successfully went on to create an empire powered by APIs.
The key concept of API is very simple; all it does is to break up your services and make them separately accessible to others through programming. There is nothing mysterious about it. But its transformation effect was enormous. 15 years ago, if I wanted to create a new service (let's say an e-commerce site), I had to do a lot by myself. Getting servers, configuring network, figuring how to analyse customer behaviour, taking payments... it was a formidable prospect.
Now, I can do most of these things really easily thanks to APIs. I call Amazon's API to get servers and network in an instant. Mixpanel's API to analyse customer behaviour. Stripe's API for payment, and so forth. Creating a new e-commerce site is suddenly pretty trivial. We have to thank API for the recent explosion in app. economy and the startup economy, and bunch of other stuff.
Why is Smart Contract better than API?
While APIs are pretty good at packaging services, it's still rather crude. For a starter, API designers have to anticipate how their services might get used and define how the API looks like. Good API designs are "generic", meaning that they can support many different, often unanticipated use cases, but a significant restriction is still there.
For example, imagine you want to start a new business called "housing consultant". You give advice to prospective house buyers, and if they end up buying the house, you'll get commission. That's of course certainly possible with just APIs. I track which houses I recommended, periodically check if the clients ended up owning the house through API provided by the government. If they did, I charge them through a payment API. This is pretty easy, but I still need to have servers. I still need to manage the contracts between the client. What if instead, I could just write up a contract that executes itself. I tell my client, "I have a house that's just for you. If you sign this contract, I'll tell you which house. If you end up owning the house within 5 years, I'll charge you $10". Once the contract is signed I can forget about it. If the condition eventually happens, payment is automatically taken.
Maybe one of my client wants to amend the contract; they want to change the condition to "if I end up owning the house for more than 3 years within the next 5 years". No problem, you can just change it a little bit and sign it. No need to worry about making notes, changing software etc. If it says so in the contract, you can be quite sure that it will be executed accordingly.
Let's say you now want to expand your business into advising people on how to save energy; for every dollar saved compared to last year's bill, you get 1%. This is again certainly possible with APIs, but much easier if energy companies offered interaction through Smart Contracts instead.
Let's say you now have bunch of these smart contracts that generates some income from various people, for various reasons, but you find out you are likely to die within a year. No problem, you can just securitise all these contracts and sell them. That itself is nothing new, with enough effort you can do this today. But it's for sure impractical for an individual to do it. With Smart Contract this will become practical, just like API made it possible for an individual to start a e-commerce site overnight.
Where does the trust come from?
"Well how do contracts know when to execute themselves?" you might ask. The easiest is to use trustable "endpoint"s, like a "land registry smart contract", or a "land registry API" provided by a trust worthy party. For example, we just tell the contract to check an endpoint provided by a government, and if it detects the condition to execute itself. That doesn't sound very magical but we still gained a lot by being able to combine such endpoints in a manner that was not possible before.
There is also some interesting ideas to generate trust in a more unconventional manner. For example, would you trust Wikipedia as a trust worthy endpoint in your smart contract? Maybe not, somebody could inject false information into articles and trigger contracts fraudulently.
What if I make some adjustments... say I pick a very popular wikipedia article (like POTUS). And we say that the information has to be present in the article 80% of the time for one year before the contract is triggered. We are almost getting there, it'll be pretty hard to pull off this fraud. Extend this concept further and you can crowd source "truth".