STELLAR lets any token trade directly against any other token, but it also includes an ability to choose a token you want to obtain some of and display how many it would take of each token you already have to get your desired amount of the token you want.
Also in STELLAR it is trivially easy and trivially cheap to create a token.
So if no-one else has yet created a token representing whatever you are interested in trading, you can trivially create such a token yourself.
You can simply create an issuer account and an issued-to account, have the issued-to account invent a name for a token it wants to trust the issuer account for and specify how many of that token it is willing to trust that issuer account for.
The issuer account doesn't even get a notification that some account somewhere has decided to trust it for something, nor the name of the thing nor the amount of the thing, but, if the issuer account were to opt to send some of that thing to the trusting account, presto that many of that thing comes into existence in the trusting account (the issued-to account as I call it), up to the number of that thing the "trust line" specifies.
Thus for example if there existed a coin named AbitraryCoin that is not on any exchanges but you wished to trade it, you could conjure into existence a token named ArbitraryCoin, trust another account for X number of them, then have that other account (the issuer account as I call it) send some to the trusting account.
You thus will have a number of tokens to use for trading ArbitraryCoin on the STELLAR platform.
You can then offer to trade that token against any other token(s) and/or against XLM itself, for example making a buy offer if you are looking to buy some or a sell offer if you are looking to sell some.
Of course there will need to be provision for "bailing in" and "bailing out" coins into tokens and tokens back to coins, but at least until volumes get large with lots of demands for bailing in and bailing out you could handle that simply by having people directly contact the issuer.
This has been working well for years now, see for example https://makemoney.knotwork.com/stellar/ and https://makemoney.knotwork.com/horizon/assets/ both of which are linked through to from https://makemoney.knotwork.com/ which gives background info about myself and the project.
-MarkM-
I've always liked Stellar. I like all the "Blue Chip" coins that have survived 5 or more years.