So let's say it is 2005, some phones have cameras, and some don't. The manufacturer of phones without cameras says: "Phones are for calling, just buy a camera, it is literally what you want".

You can be right, but the market has a final word.

Today, many people enjoy using advanced apps, that can be "installed" and "uninstalled" in one second (by opening and closing a website), without leaving any track (mess) in your computer.