Mr. V's Webpage:
History of Counting Systems
Positional notation was a huge technological advancement. Ancient peoples without positional notation in their counting systems would have to use a new symbol every time they reached numbers that were too large for the current symbols they were using. For example, even the more advanced Roman Numerals have to keep adding symbols when the numbers get too large, e.g. Super Bowl XLVIII, much more complicated than Super Bowl 48.
So, according to the TedEd talk and according to legend, we use the decimal system, because we have 10 fingers, but not everybody agrees with keeping the base-10 system, and historically, not everybody has used the base-10 system.