Are these people actually clicking on the ads and making purchases through them? Because if all they’re doing is letting the ads clutter space, but not interacting with them, does that really support the site at all?

For the most part, no, it doesn’t support the site, since most Google ads are PPC (Pay-Per-Click).

Exactly. You can get away without using the terminal on a lot of linux distros in the same way you can get away without using CMD on Windows… until one very specific thing breaks and suddenly it’s time to run sfc /scannow for the millionth time.