Actually, the article uses "open banking" correctly in this case. The author believes that if all banks used open sourced tools for exposing their data via APIs (as opposed to building everything from scratch), we'd have more connectivity - which is true.

In Europe, for example, there's 6,000 banks and there's at least thousand different interpretations of what is a PSD2-compliant API, which makes connectivity hard - you have to use an API aggregator to connect to all these APIs (unless you want to connect to each API separately). If they all just used open source libraries, we'd have less APIs to connect to, which means better connectivity.