It could cause you to get targetedTo show how many time people have been playing, I think it would be better to get a level prefix in chat or in the game tag.
Example: "(27) ExampleName1", or "(30) ExampleName2".
Showing the level doesn't necessarily tells how many time a person has been playing, but I think is a way to deduce it.
Obviously the time a person has been playing can be shown in their profile stats.
With ranks, the prefixes look cool but we have "/who".