What you are asking is why do we need information models?
The simple answer is that once you move out of a very specific, controlled context, it becomes very complex to understand the data that is collected, and you may be very surprised at the variability of data recording by clinicians.
Ultimately the data has to be coherent and queryable across many different care contexts, use-cases and organisations. To do that you need a coherent, ‘opinionated’ target for data entry - whether typed in or captured via NLP etc.
Just as a simple example - do we know if your OPCS-coded procedure code is in the context of a planned procedure, a performed procedure, or indeed not even in a patient context at all?