Because Cloudflare for no clear reason allows them to require captchas for pages that are cached anyway and thus where DoS is not a problem, and also in cases w

Because Cloudflare for no clear reason allows them to require captchas for pages that are cached anyway and thus where DoS is not a problem, and also in cases where the website is not actively being DoSed at that moment. [of course captchas do nothing against targeted attacks]