Well this is my total opinon. I don't think just a normal PPL can take the job of a flight instructor without extra training, as they won't have the experience or knowledge to answer some really smart students. Say a student put the aircraft into a spin, an inexperienced PPL holder wouldn't be able to kick opposite rudder and do the rest of the procedures like bread and butter. Mainly I think that an instructor would need the ATPL theory knowledge to answer any question that is fired at them, and situationally aware of factors that may go wrong, and also upto a CPL experienced standard. Some may disagree with me, but I guess its my only opinion.
Brian304
