And Cloudflare already does that—that's what the "Checking your browser before accessing xyz—Please allow up to 5 seconds" message means. It's clearly not enoug

And Cloudflare already does that—that's what the "Checking your browser before accessing xyz—Please allow up to 5 seconds" message means. It's clearly not enough for them though, because they then go to also require CAPTCHAs.