The French don't use the words septante, octante and nonante (from the latin septuaginta, octoginta, nonaginta) because those were considered as archaism by the experts, though we now know it is the exact opposite.
Soixante-dis, Quatre-vingts and Quatre-vingt-dix come from the Gallic (Celtic language) which used a vigesimal system (on the base of 20) instead of a decimal system like we do (base of 10).
If most of the populations use the decimal system, it is because they used their 10 fingers! The Celts somehow used their toes as well...
The Swiss and Belgium dialects are influenced by the Saxon languages and so, even when speaking French, they have resisted the Gallic ways.