One last attempt...
Student,
You have embraced the 'Effects concept' but despite shouting EFFECT at me you clearly don't understand it yet!
The 'Tactical Effect' could, indeed, be readily achieved by Tomahawk - I would go so far as to say that it would probably be the system of choice.
The 'Operational-level Effect' was to give UK air better odds in the theatre of ops. The Argentines had many more air assets than we could field and inbound Argentine strikers protected by Sweep/Escort had a good chance of decimating the Task Force. The Black Buck AIR raid convinced the Argentines to hold their AIR DEFENCE assets in the rear to protect their MOBs. This enabled the limited number of SHARs to intercept the strikers without being distracted/engaged/attrited by the Argentine Sweep. Even then, it was a close run thing so it is probably fair to say that the 'Strategic Effect' (UK recaptures FIs) was dependant upon the 'secondary effect' of the Black Buck Raids - you have only dwelt upon the 'primary effect' and are, typically, still attrition focused despite your apparent attempt to declare yourself an effects-expert. Remember, Effects are invariably targeted at influencing a party/parties and blowing stuff up is just a means to that end (e.g. convince Junta to relinquish FIs).
Just to spell it out for you as you didn't get it the first time - aeroplanes can't shoot down submarines (certainly not AD ac) therefore a sub strike would have had no EFFECT upon compelling the Argentines to hold their fighters in the rear.
I am a proponent of 'Air' but, for balance, another critical 'op-level effect' was almost certainly the 'secondary effect' of the sinking of the Belgrano. This action had primary tactical effect (sink major surface combatant = attrition) but had the 'secondary effect' of convincing the Argentine Navy to stay in port (= influence).
Might I suggest a little less arrogance….and keep studying!