Oracle 19c SE2
The purpose of a role in the database is the separation of concerns. A role should hold mainly object privileges and not system privileges if I am not mistaken.
According to the Database Security Guide, 19c
12.7 Advantages of Using Roles to Manage Application
Privileges
Grouping application privileges in a role aids privilege management …
Probably the answer to my own question: System privileges are granted to a user and not to a role, because each user might require different privileges?
Nevertheless, feedback appreciated. Thanks!