The issue was mentioned in T148757: New User Talk Messages are not included in notification.
Notifications such as 'welcome', 'emailuser', and 'thank-you-edit' do not have a primary link which is a slight usability issue:
- if users view such notifications as cross-wiki notifications, they cannot easily switch to the foreign wiki by just clicking on the notifications
- it creates inconsistency in user experience - 'user-rights' notification (although, 'pageless'), in fact, does have a primary link which allows a user go to a wiki where user rights changes have happened.