You can store it in a deep freezer without losing much nutritional value, which means it’s available on a whim without having to make a trip to the store. In many places that means you have it if you have a hankering without spending 1+ hr tracking it down first (typical if you’re not in an urban center or next door to a grocery store). I usually have some fresh broccoli stocked, but sometimes I already ate it. If you have kids, or are more remote (so it’s 2 hrs round trip or more), that is huge because you just can’t make that trip many times - too many other demands on your attention.