Is 4 weeks too early to start weaning a puppy?

Personally I'm not against gradually getting a pup used to other food sources that early but to take him off it completely??? I wouldn't do that but apparently some ppl think it's not a problem on the pup. Too me I'd have to watch the stool to make sure it's not too runny, if so then the puppy is having a problem digesting it, too hard and it's not getting enough fluids. As long as a mother is getting the extra nutrients a day, nursing does not become too draining, but should be stopped before 8 weeks entirely.