Activity Pickers - Create a Record

Summary:

It appears that the Account and Contact pickers include the Create Action on every object except activity.

Account Picker on Opportunity

Account Picker on Activity

I've tried copying the picker template and enabling create, but that doesn't seem to work. Has anyone been able to enable the 'create' action for the pickers from an Activity?

Version (include the version you are using, if applicable):

25A