They should not have deviated from the American Mathematical Society notation [1].
Compare the list of supported commands on MathJax [2] or KaTeX [3] and Typst [4].
The main purpose of LaTeX today is to be the de facto standard for scientific and technical mathematical writing.
The issue with these projects is the presumptuous simultaneous breakage of the standard with a poor handpicked mangled subset thereof.
[1] https://ctan.org/tex-archive/macros/latex/required/amsmath
[2] https://docs.mathjax.org/en/latest/input/tex/macros/index.ht...