wifi happens to be a separate component; wpa_supplicant or iwl are separate user space tools that network management tools call into; on the kernel side, the drivers and their stack are separate modules.
Yes, as it should be; while we might quibble about the exact details, I think the Linux-world network stack(s) do a good job of separating components cleanly while still giving users a good experience (if you just install Debian on your laptop, you don't need don't need to know or care how many packages it takes to make networking work, it just does).
