https://cdn .journals.aps.org/files/styleguide-pr.pdf
Page 21, little e says multiplication is higher order than division.
“The Feynman Lectures on Physics” also use this convention.
Bottom line is it is simply a convention and as long as both writer and reader know which system is being used it is fundamentally correct. Of course, if you work in an industry where a certain convention is expected and varying from it can have consequences, then you may have no choice but to follow those rules to avoid violating professional standards.