"three million, one hundred twenty-five thousand, two hundred sixty-nine"
"nine, sixty, two hundred, thousands five, twenty, one hundred, millions three"
It could work either way.
And in fact, in the early days of the Hindu-Arabic numeral system's penetration into Europe, they actually DID lead off with the least significant digit (although numbers larger than thousands were rarely used, and the archaic wordings have only survived in the ones and tens digits - if at all for a particular language).
Yes but one of those ways does not support abbreviation or interruption, or fractions. If you see a 9 digit number for example, you might want to just round off to one or two significant digits while reading it. Having the smallest components first presents obstacles to speech in much the same way Roman numerals do.
The only difference is whether you estimate this number as "about four hundred and forty million" or "about ten and five hundred million"