Wouldn't that work?
If Im not mistaken, there are many low-cap coins and tokens that share the same ticker symbol, so it would be very difficult to code an application that could differentiate between them. Without additional information, a universal converter wouldnt know which specific coin the user is referring to. Besides, for established coins, data like price and market cap is readily available through APIs. However, for less popular coins, this data might be unavailable or unreliable.
When trading on these smaller exchanges they have many bases of trading. Xeggex for instances often uses Mouse coin and Rat coin. It's one way to create value for those coins, to make people use them to sell the coins they stake on coins like Reddcoin or Strongthands.
All you need to do is know the mathematical equation based on how many of one type of coin there are to one DOGE.
Then you would know one variable, and if you just wanted to know the value of your coins in a more understandable cryptocurrency you would know.
If your exchange is using a strange currency to trade your coins with, it's hard to know where the market is in that coin at any given time. Then all you need to do is know a mathematical equation based on how many of that second type of coin there are to one DOGE. Then you can see the relationship in value or do other types of calculations.