Because some of them only want to RP the way servers like "NoobHalla" and "LoSer-RPing" (

) do.
Seriously, the main points behind Argonath are:
1. For players to get together and have fun
2. For players to get together and roleplay
Lots of people on Argonath have lost the capability to do both, and end up resorting to the extremes of fooling around nonRPly all the time or attempting "to bring his RolePlay's quality to the max" like those other sucky "RolePlay" Server's players but losing the real fun in the process.