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.
And what does ATPL and CPL got to do with kicking opposite rudder ?
Can agree with the knowledge part (although, when you're taking someone to do straight and level they won't ask you about jet engines or procedural approaches) but the handling, I think that's got to do more with your experience that your ratings.
If car drivers had a logbook, who would you let drive your brand new BMW ? An 18 years old driving instructor or someone with 10 years no claim driving experience ?
Ta