I think that there are technical, social as well as UI/UX aspects to this problem that go way beyond just "what moderation would like to have".
1. Technical
As @BlackYps said, when names are referenced in a tool in any way, the ID for that name should be lookup up and used internally as soon as possible (so if there is a UI form with a name input in the client, the client should resolve the ID right after the user inputs it).
2. Social (recognition)
Members of a social community (which FAF is) want to be able to recognize other members (even after coming back after leaving the community for some months). This is really a basic social need in any community for mainly two reasons:
2.1. Social self-policing
Every well-working social community has some form of fluid social contract between each other. Moderators/bans can and should never police all behaviour that is taking place inside a community.
Instead, the community itself enforces certain standards of behaviour. This happens automatically and is important. It is a major part of the "culture" of any community, and it requires people to be able to remember social misbehaviour of its members, which requires recognizing other player on FAF.
2.2 Social hierarchy
In every community, there is some sort of social hierarchy. In FAF there are two major hierarchies, skill and contribution. Generally, community members want to be able to respect other people inside this hierarchy. This is how legends are born inside a community and also requires recognizing other players.
For example, if a random player joins my 1200 rated games and absolutely destroys me, i will probably not react positively (i got smurfed?!). However if that random player is instead Blackheart, my reaction will be totally different because a legend player just joined my game.
3. Social (self-expression)
However, it is also true that self-expression is a good thing! Popular communities often provide a whole range of customization to how you appear to other people (not just name but usually also additional bits and pieces). Im not going to go into detail here because plenty of people have expressed how important this is to them.
4. UI/UX
The goal should then be to make both possible through UI/UX. And it is important to realize that a player ID is not sufficient to address the recognizability problem. Humans are not good at memorizing a random number per player.
One solution was already mentioned: Fixed player handle and changable player name. In addition
- the player handle must be shown in conjunction to the player name
- OR it must be trivially easy to look up the player handle for a given playername (for example by showing the handle when hovering with the mouse over a player name)
Another solution is to move the self-expression from the name to some other self-editable part of self-presentation (many games have "titles" or "status text" that is shown under the names of players).