For some of functionality, DigiD itself requires an iOS or Android app (for which you need to enter a contractual agreement with either Apple or Google and they decide whether you are allowed to install and use the app).

I understand that this particular path doesn't allow them to access further sensitive data, but it does give these corporations the power to block any individual for accessing the DigiD app.

You don't need the app for most functionality, but for a few healthcare related tasks, it's the only option, with no fallback.