The main problem here is that people who lack access to the document effectively can't participate in the discussions, if there isn't enough public information about the document accessible by other means.
You can discuss the general requirements, and paragraph numbers, etc, but there's a limit to how much somebody who has the document can quote without legal problems. Somebody else who sees the discussion can not know if the discussions contain complete enough information to "reverse engineer" the standard well enough to meet its requirements.
All those discussions about the ISO date standard involves getting information from somebody who has access to the document and who then shared the information in public. Not all documents has that degree of public commentary.
And if you need to ask about sections which haven't been previously described in sufficient detail for your needs, then you're personally relying on individual people who have access to read it and rewrite the information for you. Which is a lot of work and also legally uncertain.
Fair use standards are not all that consistent. And that's a legal defense you can use in court after already having been sued, not before. Enough for context can vary between one sentence or three pages.
You absolutely can, trivially as the huge number of discussions or the ISO date format on StackOverflow show: https://stackoverflow.com/search?q=ISO+Date
There are lots of issues with locked down standards. But copyright means they can't be publicly discussed is factually incorrect.
(Also fair use means it's fine to quote enough context for a meaningful discussion anyway)