It’s not that it “can’t”, more like it “doesn’t”. Douglas Crockford prioritized simplicity when specifying JSON. Its BNF grammar famously fits on one side of a

It’s not that it “can’t”, more like it “doesn’t”. Douglas Crockford prioritized simplicity when specifying JSON. Its BNF grammar famously fits on one side of a business card. Other flavors of JSON that include support for comments and trailing commas exist, but they are reasonably called by different names. One of these is YAML (mostly a superset of JSON). To some extent the difficulties with YAML (like unquoted ‘no’ being a synonym for false) have vindicated Crockford’s priorities.