It's weird to see such a widely used technology dismissed as not being useful (it seems we get those articles weekly on HN). There are literally millions of users and billions of dollars worth of value transacted daily[0] but this is just not good enough evidence for the critics. If they can't find a use case that satisfies them, then surely everyone else using it is just wrong.
There are $146B USD of daily transactions that go through the automated clearing house (ACH) system.
While Visa doesn't give a daily transaction amounts, going off of sources online, in 2018, it looks like they processed around or slightly more than 1B credit and debit transactions with an average value of $80.
$3.5B in daily transactions is nothing to sneeze at, but it's a relatively (very) small slice of the monetary system.
Indeed, Bitcoin is still relatively small. Its money supply (aka "market cap") isn't even 2.5% of the USD M1 money supply. Not to count all other fiat currencies.
Honestly, when I first heard of it in ~2011 I never expected it to grow as much as it did. I thought it would probably remain a small experiment confined to nerds and hackers. When it first started hitting mainstream news a few years later I was quite amazed. And while I'm here amazed at how far it got, critics are dismissing it because it hasn't replaced USD yet...
[0] About $3.5B daily for Bitcoin.