Eloqua mandatory fields

Hello,

How does the 'Make this field required' setting work on Eloqua contact fields? If checked does that mean that the field marked as required on a system level won't allow Eloqua to create a contact if that field is not filled out i.e. through uploads/form submits/manual creation or SFDC sync? I tested this function in a sandbox environment and the Eloqua contact gets created even if a contact field is marked as required but left blank. If that's the case, what's the purpose of this setting and how does it actually work?

Thank you,

Edina