Let's say you install 15 apps on F-Droid. Every time you want to upgrade your apps, you were forced to manually initiate, and then sit through, each app update as they're installed in the foreground. This was because of deliberate limitations in Android.
Whereas on the Play Store, you could hit one button to update all of your installed apps and the installations happened in the background.
I believe it was after Google was threatened with lawsuits that they modified Android to be less tedious when it comes to managing and upgrading apps outside of the Play Store.
But yes, non-Google devices make this way more difficult, e.g.: Xiaomi devices actually has a scary warnings and they trigger at each reinstall. Also, they messed up something in the install APIs so you can't update apps unattended, needing to trigger the popup to install at each update.
So yes, in general, this is not the fault of Google but third-party companies.
Unlike with apps installed via the Play Store, which can update them without needing my manual approval.