Same principle, reducing water activity (aw), is how Nutella keeps fresh for so long without refrigeration: its water activity is even lower than honey. Most bacteria need an aw of around 0.85 to thrive, Nutella’s aw is around 0.4, honey’s around 0.5-0.6. Peanut butter is 0.7, so it stays fresh for relatively long, too.
Here’s the definition of water activity from FDA:https://www.fda.gov/inspections-compliance-enforcement-and-c...