Uh... I'm not following here. You definitely can. What are you trying to do, exactly? It's true you can't uninstall the apps, because they're in the ROM. But you can absolutely use whatever you want on your home page.
To be glib: The contention was that you can't change this stuff. And your response is "That's right, you can't change it! You have to CHANGE it to change it!". So... just change it?
Fair enough, but I was trying to phrase it as a gentle joke.
I mean... you're trying to "customize" them to make them use "3rd party services"! That's the whole point! That's what you want! You want something not-Google, and you're mad that the mechanism to do so is to... not use the Google app.
I mean, you get that that's hilarious, right? Do you get likewise angry (maybe you'd say "deranged") that Microsoft has a Bing search bar on the desktop, or non-removable OneDrive integration in the file browser? That Apple sets you up with an account by default when you unbox your iPhone?
In point of fact, and being completely serious here: of all the major-vendor client platforms out there, Google Android is by far the most customizable in the sense of "removing the vendor's own app integration". Go try to swap your browser on iOS. I really don't understand why you're so upset.