User creates an article. User is the subject (the one who does the action) and article is the object (what action is applied to). See https://www.lexico.com/en/grammar/subjects-and-objects or any other resource on the topic.

Currently we have a wrong variable name in Security, VoterInterface and exception classes. The AccessDecisionManagerInterface is nonetheless correct.

I propose to replace $subject with $object in 4.3 and redeprecate (see #19969) AccessDeniedException::(g|s)etSubject in master.