I think it's more that three is the minimum number of objects required to make a series, and minimalist logos are still all the rage (will be interesting to see if AI cements this or flips it). So, three stripes and three stars to evoke the American flag without using all 64 visual elements of the flag.

I don't think we should give up one of the most natural and obvious ways to incorporate our patriotism into easily-digested designs just because a version of a foreign government that was replaced by an actually effective governing ideology 50 years ago used a common number of a common visual element in a common color 70 years ago.