As tete says, it'd be rather inefficient to do a DDoS via Tor. I think that the reason for the captcha is more related with security, to avoid spammers or bots

As tete says, it'd be rather inefficient to do a DDoS via Tor. I think that the reason for the captcha is more related with security, to avoid spammers or bots to getting through via Tor. Cloudflare explains the issue here: https://support.cloudflare.com/hc/en-us/articles/203306930-Does-CloudFlare-block-Tor- https://support.cloudflare.com/hc/en-us/articles/203306930-D...