The article touches on how later Anglo Saxons identified with Gildas, especially in their own resistance to Danish invasion. I think that's largely why the myth of Arthur became so entrenched. It resonated with later English readers, with the trials of Arthur paralleling the struggle of Alfred against the Danes.

I can't help suspect that Arthurian scholars and fans that want to place Camelot in south-central England are drawn by the ghost of the kingdom of Wessex.