That's exaggerating quite a bit. Maybe in 2005 they had that sort of insight, but with HTTPS everywhere things are different. Your ISP can only see which IPs you're connecting to, possibly which hosts you're looking up depending on your setup but DNS-over-TLS and the like will put a wet blanket on that.
Cloudflare (even without warp) has a much clearer picture of your browsing habits. Not only do they see which webpages you are requesting since they're situated as a MITM between you and a significant chunk of the servers online, they do quite a lot of browser fingerprinting and tracking for bot mitigation that could, theoretically, be used to identify humans as well.