Well, I think you all put too much emphasis on the title of Rogue
Trader. Unless the Rogue Trader is neither bright enough to listen nor
dumb enough to be ignored or played as a puppet, most of the important
dealings rest largely on the
shoulders of Seneschal, Missionary, or whoever-has-the-right-contacts
(often one of the other four archetypes). These are the people you need
to convince of your decisions as Rogue Trader. You have staff to
"convince" the tens or hundreds of thousands of crew underneath you.
(Convince can mean very different things here, depending on whether your
crew is conscripts, convicts, servitors or what have you.) And if the RT falls in that problematic zone of mediocre intelligence and overbearing egomania, they will not be making decisions for too long. Either they'll ruin their dynasty, or someone will stop them. A
Rogue Trader without the support of his (immediate) subordinates is just a
man or woman with a very old, very expensive piece of paper and a more or less famous name. Their ship will be blind, deaf-mute, starving, lame and defenseless, with unrest boiling up in its bowels.