They DEFINITELY are concerned about THEIR standing! There are benefits to being in the top 3 that no-one cares about except the Alliance it seems because they are reaping the greatest benefit!
When Mahon is rated 1, we get 20% dividends on trades done in Mahon space. That's such a massive benefit, that we're better off trading outside of Mahon space, if we're actually trying to make money. The only thing that might be more profitable in Mahon space than elsewhere is mining, and even that is somewhat doubtful.
No, we reap no tangible benefits from being ranked 1st. We don't do it for selfish reasons - we do it to promote the Alliance.