That's right. CloudFlare doesn't have traffic limits.
But if a site gets a lot of traffic it's likely a business, and businesses have additional requirements. So, the paid plans become attractive (e.g. getting the WAF protection, or better DDoS protection, or mobile optimization, or SSL) and so people upgrade.
But if a site gets a lot of traffic it's likely a business, and businesses have additional requirements. So, the paid plans become attractive (e.g. getting the WAF protection, or better DDoS protection, or mobile optimization, or SSL) and so people upgrade.