Worse than that - people will start tagging "this value is a Date" via comments, and you'll need to parse ad-hoc tags in the comments to decode the data. People already do tagging in-band, but at least it's in-band and you don't have to write a custom parser.
See also: postscript. The document structure extensions being comments always bothered me. I mean surely, surely in a turing complete language there is somewhere to fit document structure information. Adobe: nah, we will jam it in the comments.
https://dn790008.ca.archive.org/0/items/ps-doc-struc-conv-3/...
Reminds me how old versions of .net used to serialize dates as "\/Date(1198908717056)\/".