Why does vacuum sealing of foods prevent spoilage from anaerobic bacteria?
I do not understand why anaerobic bacteria, that don't require and cannot survive in air, do not proliferate and thrive in the vacuum sealed food containers

They do. Vacuum sealing can prevent aerobic bacterial growth but does not prevent anaerobic growth.
Botulism is a particularly dangerous consequence. If food containing C. botulinum spores is sealed without being properly treated (usually by heating) or otherwise by being inhospitable to bacterial growth (often due to acidity or salt), dangerous botulinum toxin can accumulate and be dangerous or fatal when the food is later eaten.