Not true at all:
1) Operators acting on a distribution: E[X], Var[X], Cov[X,Y]
2) Square brackets are used in nested parentheses to avoid confusion: [1(2 + 3) + 4]/5
3) Functionals: L[f] for lagrangian
The main reason why  isn't used as frequently as () is because most domains interpret the square brackets to mean something special. For example:
1) [x] is often used to denote floor(x)
2) [i=j] is used to denote the kronecker delta
What I must point out is you make a weak case based on myopia- for example; in 15 years of working with tens of thousands of hours of high resolution radiometrics I've never once met and talked to a dendrochronologist who's looked at the radiometric signature of individual bands of Japanese pine trees.
It's my understanding that such beasts do exist.
I think it must depend on the professor/university.