In 2014, a BitPay executive went on CNBC to talk about replacing Visa and MasterCard with bitcoin, a virtual currency.

But Visa was the piece of the payments puzzle that was irreplaceable.

Last spring, BitPay rolled out a Visa-branded card that lets consumers add bitcoin online and then spend it at stores or withdraw dollars from ATMs, just like a regular debit card.

Why are digital currency revolutionaries changing their tune and partnering with established payments players? It turns out that BitPay needed Visa’s help because most merchants still prefer Visa over a digital currency.

“While we’re constantly working to make bitcoin every merchant’s favorite form of payment, sometimes our favorite stores and restaurants aren’t ready to accept it,” Corey Glaze, a senior sales engineer for BitPay, wrote in a blog post.

It’s far from alone: BitPlastic and Wirex offer MasterCard-branded bitcoin debit cards, while Shift, Xapo and CryptoPay also rely on Visa to give the digital currency real-world spending power.

It’s a tacit admission that, despite bitcoin’s hype, Visa and its counterparts still rule the business of moving money. About 40 million outlets around the world accept Visa cards, according to RBR, a research and consulting firm. By contrast, research site Coindesk estimates that about 100,000 merchants accept bitcoin. It’s not clear how many people deposit or withdraw cash at bitcoin ATMs, but on a recent Sunday, a Coinsource ATM at Mission Grocery observed by The Chronicle went unused for hours.

Bitcoin, though, is still having an enormous impact on Visa. You’d just have to dive into the guts of the business to see it. Executives at the San Francisco company see the currency not as a threat but as a wellspring of technical innovation.

“We’re constantly learning, constantly evaluating anything that impacts electronic payments,” said Rajat Taneja, Visa’s executive vice president of technology.

Visa is now heavily investing in blockchain, the clever system that underpins bitcoin and similar digital currencies. Blockchain was supposed to cut out middlemen like Visa and MasterCard. But in fact, it may empower them to do business cheaper and faster.

In October, the company began testing a service called Visa B2B Connect that borrows principles from blockchain to allow businesses to more quickly process payments across borders. While consumers may look to choose between paper and plastic at the cashier, businesses are stuck with costly options like wire transfers, particularly for international transactions.

Bitcoin isn’t a good option, because businesses still need to pay employees and suppliers in old-fashioned national currencies. But transferring money digitally, with something like the speed and security of bitcoin’s blockchain, has considerable appeal.

“Companies don’t want to use bitcoin as unit of value but rather as a way to understand the underlying ledger technology behind it,” said Tom Brown, a partner with the banking and global payment systems practice of Paul Hastings law firm in San Francisco.

Blockchain technology relies on something called a distributed ledger, which parcels out the work of tracking and verifying transactions to a network of synchronized computers. Anyone on the network can see that an exchange occurred; that view allows for trust and prevents hackers from stealthily altering transactions.

It’s a shift in mind-set from the old days when Visa was a consortium of banks that moved money on a private exchange.

“When we look at blockchain, we can see a lot of interesting possibilities,” Taneja said.

In some ways, it’s a throwback to the earliest days of Visa, which founder Dee Hock saw as a “chaordic organization” — a synthesis of chaos and order, with peer-to-peer aspects — that might one day create a universal currency. While Hock left in 1984 and Visa changed in the ensuing decades from a cooperative of competing banks to a regular, for-profit corporation, it’s still got glints of his vision.

The fact that Visa might one day discard the money-moving networks it helped build in favor of an upstart technology born from the Internet could only please Hock.

“Only fools worship their tools,” he once wrote.

Thomas Lee is a San Francisco Chronicle columnist. Email: tlee@sfchronicle.com Twitter: @ByTomLee