Because the registry holds configuration data, and Application Support holds various helper tools and other random crap?

The closest analogue to the registry on macOS are the ~/Library/Preferences and /Library/Preferences folders.

It's not a directory tree you can just browse in the filesystem, it's a few database files. Idk much about Windows, but at first glance I like how you can browse the Windows registry all in one place without digging through other files.