I do as it stop the compost falling through at first and then the holes clogging and promotes good drainage.

Or you can use bits of broken clay pot or lumps of polystyrene such as come in packing if stones are not available.

The polystyrene helps reduce the weight of big pots too.

I don't always, specially for summer bedding, unless my pot has no drainage, in which case I place about 3 inches of gravel in the bottom.

I have this theory that with crocks in the bottom I dont get infestations through the bottom of the pot

I like your optimism, Drc, lol! I find a jeycloth in the bottom helps with that.

Or a bit of weed suppressant which was a suggestion of yours I have used Bamboo.