poe.trade supports Currency Seller´s ?!

I do not trade much any more (like the Ssf)
But does the official site indexes forum based shops or only the ones set up by premium tabs? As if the later, that would be against the "equitability" of the game to force people to use it.

I use poe.trade primarily because for some reason the official trade site often does not show all the listings for items, particularly magic utility flasks. Either when trying to price my own flasks for sale or when looking to purchase from others, poe.trade has more listings. It is not exclusive to just flasks, I have experienced this with belts, boots and amulets as well and I am not sure why that is. So I continue to use poe.trade to ensure that I see all the listed items that simply never show up on the official site no matter how often I hit search.