The challenge is then picking the subset of LaTeX. Then maybe someday someone would write a web-LaTeX preprocessor with macros and the like.
I guess one more wouldn’t hurt.
If you mean something else, please elaborate :)
I do not encounter TeX users who write their own macros often.
But they use packages that they got off CTAN that were written by someone who is not at central office (not that there is a central office, but one would be needed if you stripped out the ability to write serious macros since there would have to be someone adding approved features).