Why the single 4.7-inch anti-aircraft mount faded

Why was the single 4.7-inch anti-aircraft mount such a short-lived idea?

It did not meet expectations and was overtaken by more useful 4-inch and 4.5-inch systems.

The single-purpose 4.7-inch anti-aircraft idea did not perform as hoped. The Royal Navy already had 4-inch and 4.5-inch systems available. Pouring resources into the weaker intermediate design would have diverted effort from weapons that were already replacing it. Its short life reflects the opportunity cost of trying to rescue a system that had lost its place.