Why request a statement ?
To study
Higher education institutions are autonomous in their admission decisions. Some may ask for a certificate of comparability to better understand your language abilities.
To work
The certificate of comparability can help an employer better understand and evaluate your language level. Each employer is free to demand the certificate or not. The certificate of comparability is not an authorization to practice a regulated profession, access to which is subject to possession of a specific professional qualification and/or registration with a professional organization.