By whom and why would the sites get DDOSed if they didn't use Cloudflare? Am I wrong to assume that internet traffic is just as trackable for the internet provider if the server traffic first visits Cloudflare vs just using whatever the provider...uhhh...provides?

Mind you, while I can follow a logical argument, most stuff concerning networks like the internet still feels like magic to me for the most part. We use Cloudflare because, after reading up on it a little bit, I got the notion that it would likely improve our connection speed and especially the loading speed of my gf's webtoon sites. But that's about the extent of my knowledge.