This would mean that on one hand (literally) you count the phalanxes (12), while on the other hand you use a completly different system and count your fingers (

This would mean that on one hand (literally) you count the phalanxes (12), while on the other hand you use a completly different system and count your fingers (5). Why would you ever use 2 different counting systems? It seems that your argument is more in favor of base 25(=5 * 5) or base 144(=12 * 12).