A recent ban on certain customers has motivated Eric S Raymond (ESR) to write on how dangerous software as a service is to our freedom [ibiblio.org]. It's a brief blog post where he goes through a specific case, points to the pre-existing warning signs that are ignored, and summarizes:
It’s 2019 and I feel like I shouldn’t have to restate the obvious, but if you want to keep control of your business the software you rely on needs to be open-source. All of it. All of it. And you can’t afford it to be tethered to a service provider even if the software itself is nominally open source.