That is not the point. If referees were not allowed to exercise professional judgement and applied everything according to the letter of the law, there'd be chaos. The cognitive process involved in awarding a penalty are different from awarding a normal foul for obvious reasons, unless you are a shit cold hearted referee like Mike Dean. This is why you will never see a referee consulting a linesman on a normal foul but will when supposed infringement is a potential penalty offence. The guidance they are given to support the rules lay out what to look for especially when awarding key events like a penalty. But let's oversimplify things and pretend otherwise. The rules are worded the way they are for a reason and yellow card offences, as an example, cover the broad spectrum of unsporting behaviour. The referee has to weigh up the evidence and decide if it warrants a caution or a penalty offence. The point of this discussion which is the City penalty is that it certainly wasn't clear cut and the evidence was not strong enough to warrant one. You could also argue simulation on De Bruyne's part.
