For humans, social status is much more than just an aggregate estimate of competence/reliability/trustworthiness. It motivates us, distorts our thinking, plays a key role in our politics, etc. To take just one example, I suspect that the main reason it's so hard for most people to change their mind is because they don't know how to do it in a way that preserves their status. For many people and social groups, admitting you're wrong means losing face, and most people don't like to lose face, so they resist publicly changing their mind.
(This is another reason why status differences may be counterproductive for rational communities... they could create an incentive for high-status people to not change their mind about things, since they have something to lose. The evidence may very well justify thinking one thing one week, then something else the next week, then something else the third week. But if you're changing your mind about critical issues every week, it won't be long before typical humans take you less seriously. Which is unfortunate.)
Also, this doesn't sound like your true objection to me. It doesn't take very many more bits of information to transfer 3 estimates on each of competence, reliability, and trustworthiness than a single aggregate number. And people communicate specific info all the time ("how good is X at Y? do you trust Z?"). It's not obvious to me that a single aggregate quantity is frequently useful. Let's say I introduce a friend to you and say his status is 67/100; was that useful information? (And in practice, peoples' status is often determined by relatively silly things like how many friends they have, what status they're perceived to have, how confident they act, and how confidently they talk. Another reason status sucks: it gives people an incentive to make confident predictions; see Philip Tetlock's work on how confident experts are more likely to be wrong and more likely to be quoted in the media.)
(I don't think I've got a clear idea of how best to make use of humans' status wiring; I'm just kind of exploring different ideas at this point. But it seems like an important and neglected topic.)
Another risk of status differences is that good ideas from low status people may get ignored.
My impression is that LW is fairly good about taking people's behavior one item at a time.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.