Most of the apps on my phone are from FDroid. This does not mean that you can have a phone with any comparable level of functionality without relying on Google. You can see for yourself by installing a stock android ROM with no google play services or microG.

How can you possibly think this is a rebuttal? Whoop de do, there exists an also-ran OSS marketplace on the platform. In what way does that rebut what the grandparent said?

There exists a repository named Cydia for iOS with no ties to Apple, therefore iOS is an open system? Google moves essential parts of Android to the proprietary Google services and can easily enforce restrictions for smartphone manufacturers, so 3rd party stores depend on Googles benevolence.

F-Droid has a major flaw, in that Android (as of now) doesn't allow auto-updating of apps outside of Google Play. I only install a limited number of apps from there for that reason.

Right. And microG is a perfect replacement that works flawlessly.

You see where this is going. Google has moved _so much_ functionality into play services that Android as a platform is losing features every day if you don't have it. It's fine for fully local applications, but should you rely on location services, dynamic module delivery, any maps service, etc, you are utterly fucked.