We will have to agree to disagree.
Someone who has had professional training, learned to follow and reproduce another's choreography, learned to partner, learned specific rules for particular dancing and to work in groups of strangers and reproduce all that night after night is always going to have a massive advantage in competition ballroom dancing.
They are not comparable to someone who has taught themselves freestyle dancing and makes videos of those dances (which can be stopped, edited and retaken many times) and sometimes dances with friends in those videos.
I didn't consider Karen Carney a ringer either because her dance 'training" was the dance lessons and competitions that millions of children (including probably most of the celebs) do at school and she quit those lessons at 15 in favour of football.
Neither are even slightly comparable to a performer who is professionally trained in dance, dance styles, choreography, rapid learning of other choreographer's work, live performance, dancing with partners, small groups and ensembles and in some cases are professional teachers (albeit Layton was the extreme end of ringer-ing).