Why is the story that Betsy Ross designed the first United States flag considered unsubstantiated?

The story that Betsy Ross designed the first United States flag is considered unsubstantiated because it lacks contemporary historical evidence and relies entirely on family anecdotes.12

The legend was popularized in 1870, nearly a century after the flag's adoption, when Ross’s grandson, William Canby, presented a paper to the Historical Society of Pennsylvania. Canby claimed that George Washington and a committee from the Continental Congress visited his grandmother in 1776 to request the flag and that she suggested using five-pointed stars instead of six-pointed ones.1

While it is documented that Ross was a seamstress who made flags for the navy, there is no official record or primary source confirming her involvement in the design of the national flag. Conversely, there is strong evidence suggesting that Francis Hopkinson, a signer of the Declaration of Independence, was the primary designer. Hopkinson even petitioned Congress for payment for his design work, though his request was denied on the grounds that others had also contributed to the final product.132