If I had a dollar for every (usually childless) turkey who wholesale believes the interesting, yet under-evidenced hypothesis that ‘germs are good, therefore let kids eat off the floor’ I’d have nearly 100 dollars.
I’ve even been called a ‘germophobe’. Let me add some perspective: I own two dogs, who are allowed inside for part of the day. I let my son crawl around on the floor, and let him put things in his mouth as long as they are not obviously filthy. I like playing outdoors, and I think it is normal for kids to be a bit dirty. I also believe the rather more established theory that most colds, flus and gastro infections can be prevented by good hand hygeine, which basically means washing hands with plain soap and water before meals, and after taking a dump or cleaning up a nappy.
I really doubt that one needs to eat a spoon of earth a day to build up a proper immune system. The new fashion that all child cleanliness is bad seems more socially and politically motivated than based on sound evidence.