Thanks for explaining, now I see what you mean.
And I can see where such a feature could be useful for members that “wear many hats”.
If I am a cook, painter, photographer and guitar player, but can only choose one at any given time that is used site-wide, it would be a tough choice to make for the “hobby” forum.
Although it could be useful to allow more control over what title is used where, I fear it would add quite a bit of complexity to to the code base.
I’m thinking a plugin that uses custom user fields is probably the better first step for this feature.