In MergeTB, when a materialization is created, all nodes that are capable of having some sort of user account have accounts created for every user in the project to which the experiment belongs. This is often highly convenient. However, this is not, in general, the way that software is deployed. When real world systems are deployed, the developers of the system do not have accounts in deployment environments. In some cases for ‘operated’ systems, there will be operator accounts, but this is by no means a universal rule.
So it would seem that placement of user accounts on nodes should be configurable. At the very least to support experiments in which the current automated user account creation would violate the validity of the experiment environment and experimenters then have to go in and explicitly delete accounts that were automatically created.