Blockchains do have instant use cases. Remittances being one huge example, for many years blockchains were the cheapest way to send money across borders, and for many countries they still are, though they've put a lot of pressure on banks to reduce the prices of remittances.

Other types of digital international payments have also been made a lot easier. You don't need to sign an agreement with a credit card company or a bank to start accepting money from a blockchain, you just run a node an you are good to go. Especially for use cases where payments are typically high risk or denied altogether (shipping expensive hardware, adult entertainment, or any business with a generally high fraud rate and chargeback rate).

Blockchains also allow for completely transparent, auditable, provably fair gambling, something you simply can't achieve in the physical world.

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A lot of the blockchain projects that have kicked off do not understand the limitations and uses of blockchain technology. For example, decentralized land ownership and decentralized voting are both things that you fundamentally can't get fully secure using a blockchain. Land is a physical asset, and it will always be a government or police force that ultimately decides who owns a property. The blockchain may say one thing, but that result has to be defended in the physical world by someone who agrees with the blockchain results.

Voting is the same way. Identity is inherently centralized, there is no way to connect a physical human being to a single identity in the digital world unless there's some centralized entity like a government managing the ID system.

One big use case that's around the corner but needs more foundational technology work is point of sale payments. It seems like the adoption curve has been going backwards on those for blockchain, however this is because layer 1 fees have been getting more expensive, and attackers have finally started exploiting weaknesses like zero confirmation payments, something that originally a lot of blockchain proponents asserted was secure (core developers never endorsed this notion, however core developers rarely had control of the blockchain narrative). As more user friendly, more secure, and more scalable solutions like the lightning network come online, we will see point of sale payments using blockchain technology pick up again.

We're still probably 1-2 years out from the lightning network being production ready, so merchants are still generally discouraged from using it for daily business. But it's going to get there and when it's ready the scalability will be on the order of tens of millions of daily users.

We have the cryptography and technology to get from tens of millions to hundreds of millions, but again that's technology and research which is just now coming out, won't be in production for another 5-8 years by my estimations.

Whether or not you choose to believe it, there are tens of thousands of businesses out there today tackling markets and buyers that would be completely unavailable to them without the use of blockchains. And that's because blockchains make payment rails viable that simply aren't viable when you are stuck with traditional systems like credit cards, paypal, stripe, and bank transfers.