I found something. Good, at least it shows I am not imagining it.
Unlike some of the other theories of a historical Arthur discussed here, few would now be tempted to describe Morris’s ‘Arthur the Emperor’ theory as a respectable work of scholarship in its totality and especially with regards to Arthur. As has been argued at length by two distinguished reviewers, it is “an outwardly impressive piece of scholarship” which “crumbles upon inspection into a tangled tissue of fact and fantasy which is both misleading and misguided.” (Kirby and Williams, 1975-6). This view is supported to some very large degree by Professor David Dumville in his justly famous attack on both Morris and Alcock (1971), ‘Sub-Roman Britain: History and Legend’, where he demonstrates the utter invalidity of Morris’s approach to the sources which renders his ‘reconstruction’ of events almost completely worthless (Dumville, 1977). Another reviewer, Professor James Campbell, is slightly more generous, recognising the good hidden in among the bad, but he too admits that The Age of Arthur is a book so misleading, so idiosyncratic, so full of problems, difficulties, and traps for the unwary, that it should be used only by professional scholars – already familiar enough with the ongoing debates and the primary sources to ignore the many unreliable theories and passages in the book –, and that it is manifestly not a work appropriate for amateurs or newcomers to the subject (Campbell, 1975). Unfortunately, this seems to be just the category of readers who make most use of the book nowadays, with very few professional scholars ever now returning to the tome due to these immense problems.
From
http://www.arthuriana.co.uk/historicity/arthurappendix.htm