You still don't get it do you? No one has ever said it is not possible to rp different types of realms and life, it is however important to many of us that the system to which we are bound to operate with gives us the tools to actually make it as realistic as possible, in the case of the nephilim, having a big ship like that, with the specific design, and with the actuall capability to maximize our rp is in big importance. Yes, a bison could act like a battleship, but it is a self inflicting paradox when you realize that it is infact just a bison, and such realization prevents you to move forward. RP is often my number one choice, however - given the universe to which we live in, pvp is bound to occur one way or another, and it is in my best intrest not to get myself killed if infact all other measures fail. Remember, this aint just about you, its also about the people you meet.
To avoid any language barrier here
you may rp a nephilim with a bison, but a nephilim wont go down with 3 shots