Cunctation* to You.
OP’s blogger is right, in sofar as Spitfire had less payload/range than others, and fabrication/repair were not at agricultural levels. Rather like Porsche 911.
Spitfire production was given priority 3 times: was that sensible…on the facts of the day?
1. 3/6/36: 600 Hurricanes and 310 Spitfires ordered. Much effort by Air Ministry then to bolster the muddy marine carpenter: Short’s, Westland, Cunliffe-Owen, Folland, General A/c, were all brought into the Production Group. If the design genius had worked for a lesser entity than Vickers, A.M. might have transferred the order wholly to a proven, high-volume metalworker. But by mid-1938 parent Vickers had adequately resourced the job. So: sensible.
2. 8/38: Lord Nuffield was appointed Project Manager to build auto-style high volume Castle Bromwich Aircraft Factory. 12/4/39: A.M. changed its intended product from Westland Whirlwind to 1,000 Spitfire Mk.II. (Beaverbrook, MAP, 20/5/40 sacked Nuffield and inserted Vickers-Armstrongs: separate controversy). OP’s blogger would have preferred Whirlwind payload/range and cannon: shall we here accept that few or less would have been operational, 7/40. So: sensible.
3. MAP’s S.Marston Factory was assigned (at first, in part) 2/43 to V-A and 2,962 Spitfire F.21 were ordered from there, 5/43 (more and Griffon/Seafires later). We know now…but not then, that many would prove superfluous, as Big Hawkers and effective US types would cascade. So: on the day: sensible.
(*UK 1936/38 Policy was not then described as Appeasement: this odd word implies softly, softly, catchee monkey).