His point isn't about commas over periods, it is that "5000000" without any delimiters is hard to read.

To be fair, considering China and India are included, I think that's more than half the world population. China, India and the US make up more than 40% of the world population alone, apparently:

https://en.wikipedia.org/wiki/List_of_countries_and_dependen...

(The US is the 3rd most populous country by the Wikipedia hivemind's reckoning. Who knew?)

Yes and i dont use Arabic numerals. Whats it in Roman?