I understand all that. My point is there should have been a carrier based fighter capable of matching the latest land based fighters from Europe as part of the AFD concept and execution. When you develop a battleship you don't sort out the guns after the ship is built, but as part of the overall design.
AIUI you are completely misstating the "concept" behind British Aircraft carrier development in the mid to late 30s
(when the RAF was still in total control of aircraft types and numbers supplied to the RN)
Firstly, there was
no British "AFD=Armoured Flight Deck" concept but rather an "Armoured Box" concept
designed to give protection of the sides as well as the top side of the ship.. and especially the hangar.
Secondly, there was no need for as you so elegantly put it "a carrier based fighter capable of matching the latest land-based fighters" precisely because these carriers would not operate within the range of land-based fighters by day. (One reason the RN also developed night attack capability)
That also meant they would be out of range of dive bombers, which the RAF, in any case, dismissed as ineffective.
Even land-based torpedo planes were under-rated, another method that the RAF was not interested in.
The main existential threats to RN carriers would be enemy surface ships (which even the RAF could understand)
and longer ranged high-level bombers (which the RAF loved to the point of obsession).
Wrt to surface gunfire, the vertical armour need only be planned to keep out light cruiser shells.
Carriers would be escorted by RN heavies if enemy capital ships were a threat
In any case, a Carriers best protection would be to remain undetected by shooting down enemy recon planes
and by detecting enemy ships while they were still at a distance.
Hence the 1938 specification which resulted in the Fulmar: robust, good armament (for its time), reasonable range, able to perform recon/patrol itself but no dogfighter.
If the carrier was detected and an enemy air raid was mounted, the British were convinced it would be numbers of high-level bombers attacking in formation but with no fighter escort because of the range.
Therefore the same type and numbers of fighters could deal with some of the attacking force
and the carriers own heavy AA would disrupt the rest (even if few of the attackers were hit).
The horizontal armour was specified to beat those few bomb hits that might be achieved.
However, most of the British assumptions proved invalid ...
They did have to operate carriers in range of land,
they could not always provide an appropriate escort
etc
Above all aviation advanced faster than expected.
Enemy planes got faster, had longer ranges, carried larger weapons and were available in larger numbers.
The "Armored" carrier DID prove useful, but a high-performance fleet defence fighter WAS needed.
The SeaFire was a panic reaction ... understandable given Britains position in early 1941
.. but in hindsight NOT the best decision even then.