You mean what Docker for Desktop can't do? It does have a few unique features (for example automatic HTTPS for containers) but that's not the point. The point is that it's much faster, the fan runs quieter, the battery drains less, memory gets hogged less, it crashes less, the UI is smoother, the updates actually work, and it keeps improving at a steady pace. The fundamentals just work a lot better.
I second this. We switched everyone at Instacart over from Docker Desktop to OrbStack because it was so much faster, easier on the battery, and simple to use. It was particularly noticeable on our older Intel MacBooks. Simply running Docker Desktop at all left mine noticeably hot and fans would regularly spin up for simple containers.
The difference is much less stark on Apple Silicon, but last time I checked OrbStack was still dramatically faster across multiple metrics.
Our local dev process was pretty heavy though. If you're doing simple, small containers and not copying a ton of things in, then you probably won't notice a difference. It's nice that the GUI app is not bloated and slow though.
I'd take this article with a grain of salt when it doesn't even mention it, or any of the other alternatives.