Excellent point, Flying Clog.
Something I can add to this is that not all situations can be written up in the SOP. For example, there are plenty of nonstandard technical failures which have no associated procedure - and correctly identifying the issue and its consequences is vital. That's where it's helpful to have an in-depth understanding of how the aircraft works. So, the question bank learner who's memorised which buttons to push to get from A to B without much understanding of what they do is only a good pilot on a nice day with everything going routinely. Although it's a matter of fact that most days are just like that and it's a routine and repetitive job for most of the time, the moments when the brown stuff hits the fan are when you tell the men apart from the boys.