Yes there is rng boxes like on retail, yes people donate to the server to get credits to sell on AH.
However, seeing as there's a lot of labor for everyone, it generally is easy to earn gold, and therefore it helps that the rng boxes/credits increase the availability of certain items (like lucky moonpoints, snowflakes, lunarite) which then results in a price drop in AH.
In the end, it helps progression, if people are patient enough to save gold instead of buying things when it's more expensive.