Attempting to auto link on names can not be made to work correctly.
- Names are not unique
- Names can change
- People often use shortened forms when linking by name for convenience
Under only constraints 1 and 2 it would be possible to globally parse the data and fix most cases every time a user changes his/her/its name.
Once you throw in the last fact, the problem becomes AI complete.
I started out ignoring the suggestion for a new markdown syntax. But that has become the focus of the comments on this answer so perhaps I should say something about it.
That is something that could be made to work (and in the comments, too!), but it would require another database query for every name so linked. I'm not sure that it is worth it.
For myself, I do a very modest amount of inter-answer linking, and always copy and paste the link as well as making the text reference the other posters current name. The problem is that I often write comments to another user. I suspect that busy threads see dozens (or more) of such instances including the question and all the answers. Ouch.