I also feel like it's not accurate anymore.

Java doesn't run on iOS. Period. In fact it's almost impossible to build an iOS app using Java - the only ways to do it are essentially to transpile Java to some other language, so Java isn't running on iOS at all.

iOS is one of the most popular operating system in the world by any measure. It supports a lot of languages.

But not Java.

iOS is one of the most popular operating system in the world by any measure.

iOS has a market share of around 30% worldwide and Android being close to 70%.

They said one of the most popular operating systems by any measure.

It beats out all the BSD flavours, RedoxOS, TempleOS, MacOS (by an order of magnitude, I might add), Haiku, AmigaOS, Minix, just to name the more known ones. If you discount servers, it's nearly 30x as popular as Linux. It's on track to having more users than Windows. It gets beaten only by Android, Windows, and potentially Linux because of all the data centers (honestly kinda hard to get a real number on how many Linux servers are out there, especially since a lot are also virtual machines, etc)

As far as operating systems go, iOS is in the top 0.5%, so definitely one of the most popular.