As per the API document at https://circleci.com/docs/api/v1-reference/, we have the ability to get all projects that we are "following". This is:
However, this does not provide the ability to search all projects that we have access to by username.
A use case of allowing search by username is for github organization when rotating secrets. If a user is part of an organization, he/she may want to search for all projects that he/she can see in that organization (aka. username) to obtain further information about that project.
For example, let's say 10 out of 20 projects have a secret in environment variables. This secret needs to be rotated. An ability to search for all projects will allow us to iterate through all projects and rotate the secret if found. Without this ability, we may miss a project that contains a password.
NOTE: This is not the same as using a global environment variable because the secret should only be present in specific projects and not globally.