I had to think about this a bit, but in a way actually you are both right. The climate myth about Edmonton is incredibly strong, I suspect there are people elsewhere in Canada who really believe we get 4 to 6 months of sold minus 40 here, just because they heard it was that cold here one day in the winter. Seldom do you read an article from someone from somewhere else about Edmonton that does not include either the words cold or frigid or something similar in it, regardless of when they come here. The cynic in me thinks maybe they get a bonus from Calgary tourism for that.
In reality, I would describe our weather as quite variable. We seem to have spells of colder days, broken up by much milder days in the winter. Our actual winters temperate averages are similar to Ottawa and Quebec City. Our growing season is longer than many other places in Alberta and many other places in western Canada. However, in so far as people from elsewhere continue to believe or perpetuate this myth, yes it can be a detriment to us.
I do think at this time, the last few years of languishing or low oil prices have more of an impact than the climate myth. We had the same climate in 2008 to 2014 when things were buzzing here.