One of the big advantages of access tokens is the fact that you do not have to create a user in Artifactory to use them. When creating a token, you can specify a user name that does not exist, and Artifactory will create a transient user that will only exist as long as the token is valid. This can be useful when providing access to different tools such as a CI server coordinating a build without having to manage fake user accounts. This method is also more secure since you can assign a new token for each "job" that the external tool runs.
Artifactory Administrator Only
Note that this feature is only available for Artifactory administrators, since non-admin users can only create tokens with themselves as the Subject.