As a JIRA Portfolio administrator
I would like disable "Everybody" as permission access to new plans in my platform
so that authorized users must be input on a per-plan basis and then the list of plans for every user only includes the ones strictly interesting for him/her.

Even though the option "Private (only me)" is the default in the creation dialog, many users may be tempted to use "Everybody", as it suggests an easy access for colleagues. In large instances, using "Everybody" creates long lists of uninteresting plans for most users.

Having or not "Everybody" in the plan creation dialog could ideally be set as an administrative feature at platform level.
As a complementary feature, plans could allow admins to turn them back to be "Private (only me)"