Or maybe they were going to use it as filler? Most prescription drugs are mostly filler too, and just micrograms of active substances in many cases. But if you make a tablet of just the active stuff it's too small to handle.
I don't know much about extacy but I assume it's similar?
The result is the same, but most drugs (prescription and otherwise) are more in the milligram range. For ecstacy/MDMA an effective dose is usually on the order of 100mg.
Or they were melting down small candies to make one large one, a la Barry Lewis on YouTube.