Bottled out?

The top shelf of my fridge is full of jars and bottles – jam, marmalade, chutneys, pickles, salad cream, etc and it started me thinking. Years ago there were no preservatives in these items and we stored them in our cupboards. Now with preservatives added we have to keep many products in the fridge after opening and then use within a few weeks. Can someone explain this, please? Gill Preston, Portsmouth