Complexities with restricted numeral systems

The cognitive advantages to retaining a restricted counting system (without exponentiation) even as a more complicated one is being developed are not immediately obvious, but follow from the information about upcoming complexity that is implicit in the use of distinct numerals. Kanum, a language from the south of New Guinea, where "systems with limited extent" are widely reported, has base-6 counting systems with full use of exponentiation in one system, and no possibility of extension in another. The evidence suggests the more complex systems were internally motivated, yet the simpler systems have not been abandoned.