That's sort of true. Prior to Greenlight, publication on Steam was dependent on having your project reviewed and approved, which meant there was often a lengthy wait to get a response after submission (if you got a response at all), at which point your game might have been approved for sale, you might have been asked to make some changes before receiving approval, or your game might have simply been rejected. Greenlight allows anyone to publish as long as they're willing to pay the $100 fee and they get enough votes.
It was my understanding that anyone could release on Steam until greenlight came out.
The result was that most people didn't get onto Steam previously. Even with the $100 fee, Greenlight should present a much lower barrier to entry.
Publishing on iOS requires a $99/year developer membership fee. Although user ratings and reviews help to a certain extend, Google's Play marketplace for Android is full of low-quality and poorly functioning apps. You're not really worse off with Steam than you are with iOS, and as cowsarenotevil says, "works" is a term than can loosely be applied to both the iOS app store and the Android marketplace.
That's how iphone/android work
Personally, I think the $100 fee is a good thing, and I don't think it's a particular excessive amount of money -- perhaps they could consider some system where part of the money is refunded after publishing rather than the whole amount going to charity however.