It's not 150 unique apps. The article says:
It’s not just Netflix, Spotify, and YouTube that don’t have apps for Apple’s Vision Pro at launch.(...) As of this weekend, the AR/VR device’s App Store has just 150+ apps that were updated for the Vision Pro explicitly
You can watch Netflix on the Vision Pro in a browser but they didn't create a specific app for it like for example for iOS. 150 other apps were updated to run on the device. We're not talking about apps that run only on Vision Pro, just apps that have specific Vision Pro version. It's like if when Apple released the iPad only 150 apps were tested, maybe slightly adapted and marked in AppStore as iPad compatible.
150 is nothing. There are millions of apps in the AppStore, all (if not all, most) of them could be updated to run on the VisionPro and developers of only 150 bothered to do it. That's terrible result.