It took me a second to get it too. It’s just a joke that’s worded like the caption on an old fashioned 1 panel cartoon, like Far Side.

e.g. if I’d posted a picture of a man surrounded by an angry mob, he might have commented something like “in hindsight, Greg shouldn’t have sold a counterfeit Mona Lisa to ALL the museums in town.”

How come the crops won’t grow?

They came from behind, it’s a surprise round.