Did pandoc not convert org files to HTML correctly?
IIRC last time I tried this (long ago) there were a number of gaps in things like org-mode tables.
At the limiting case, the (common or uncommon) elisp extensions (e.g. org-babel) will likely never be processed by third-party tools.
The one problem I have with pandoc is that when using word export, it loses the table and figure numbers. Mind you, at least I only have to put those in outside emacs :)
To me that's got the same drawbacks as "not standardized". If not all of the existing tools support the standard then there are several de facto standards.