Application without cover letter?

Hello,

Do I have to write a cover letter for every job application?

Are there any websites that offers a different application procedure? For example, applicants upload their detailed cv and work experience, click on the jobs that they would like to apply to. Then, the employer quickly checks the CVs of all applicants, and filters out most of the applicants. The employer then tells the remaining applicants to write a cover letter. This way, applicants won't have to write cover letters for jobs they will not get accepted to anyway...