The original statement was about coverage of the breadth of the specification: if you're consuming data you need to accept everything the specification allow, but if you're generating data you should be producing as little of the specification's productions as you can.
This does not work when the format is mostly unspecified and the vast majority of what you'll find in the wild is a tire fire.
This does not work when the format is mostly unspecified and the vast majority of what you'll find in the wild is a tire fire.