Full names are the real identifier of a person, and not the username.
To deliver a more ‘human’ experience, could we resolve Full names against users against their activities, leaderboards and bring the @mention Full Name approach, LinkedIn style because no one really memorises usernames to loop in the person.
This goes hand in hand with the User search initiative. This idea is more about making Full Names a display priority across the UI, over usernames as it is currently.
And yes, on a separate discussion/Idea I’ll request the username field to not accept spaces in the username.