If you would make that to work and the site would not have a timelock or banning enabled, it would not be stopped. The problem with spammers and crackers are n

If you would make that to work and the site would not have a timelock or banning enabled, it would not be stopped. The problem with spammers and crackers are not people like you, but rather the ones ho hammer sites using thousands of bots running behind proxies, which send raw POST data to the action url of the site's form. Even with CAPTCHA the bots are able to successfully send the POST data using OCR, which recognization rate varies from all around 10% to high as 80% depending on the CAPTCHA system used. For this reason, even if your method would work it is lesser bad for the website owner. Every solution has its weaknesses, but it is rather subjective which has the least of them.