How to configure referrer filtering on Application level, instead of on API level

Issue

• 3Scale API settings allow to activate 'Require referrer filtering', which forces developers with access to the API to indicate allowed domain / IP referrers. We have a use case where not all developers (applications) would benefit from referrer filtering, but some would. This makes us wonder if it would not be better to bring this setting to a lower level (away from the API but on the level of the application).