Money is money, and companies want more. Of course if they notice they can both sell you the product and have you be the product, they'll ask themselves "Why no

Money is money, and companies want more. Of course if they notice they can both sell you the product and have you be the product, they'll ask themselves "Why not both?" The login thing is also probably partly because it does genuinely make the user experience better - log into a computer, To Do has your tasks, OneDrive and OneNote start fetching your notes and files, Edge seamlessly syncs your browser history, and so on. Things Just Work™. MS has a cloud-based clipboard and Edge has a OneDrive-backed AirDrop clone. All of that needs accounts to function properly.