That’s a well-known argument, but is based on the fallacy that coming through Hong Kong makes the chefs or the tastes of the diners superior. Although Vancouver and Toronto have a lot of chefs from HK, San Francisco was, and is, a popular destination for chefs directly from Guangdong, including Shunde. Most of the Cantonese chefs and cooks in Chinatown learned to cook in their homeland (or at cooking school that existed in Chinatown in the 50s) and were never impacted by the tastes of Hong Kongers.
I spent three months working in HK in 1997, and to me it seemed to me that while the Chinese food there was very good at the lowest end (i.e. street food) and at the high end, there were was a lot of mediocre fare in the mid-range places. It’s a seller’s market over there, and at 6:00 or 7:00 in the evening people would be lined up at the neighborhood restaurants (in Kowloon, where I worked and stayed) that wouldn’t have attracted extraordinary notice in San Francisco’s Chinatowns.
Even if one accepts the notion that Hong Kong’s most celebrated chefs migrated to Canada, not the U. S., the argument for their food’s superiority is grounded in an auteur theory of cooking Chinese food which not all lovers of traditional Chinese food will accept. The word “innovation” is a smoking gun in that argument, if you ask me. Innovation isn’t necessarily improvement (just ask almost any Chinese who has eaten at Mission Chinese Food). Lettuce cups and walnut prawns do not represent the apex of Cantonese cuisine, and the Chinese did not invent mayonnaise.