They might be the most common because they're the easiest, but there are also still plenty of people actually paying for the games. I'll never be convinced that piracy is an actual threat to making money. Piracy has never been easier, just see /c/piracy@lemmy.dbzer0.com for proof, and yet pretty much all forms of entertainmment are as profitable as ever.
iTunes Music Store (it’s still around but can be hard to find because of Apple Music streaming service)
Amazon’s music store (but it’s crap quality and they put audio watermarks in it - don’t use them while the two above options exist)
Comixology before Amazon bought and deleted them
Occasionally there are websites where you can purchase video content for download, but it’s quite rare. I remember buying anime from such a site before.