I feel that the Maritimes are somewhat simplified here, especially Newfoundland and Labrador which has some of the most distinctive accents on the continent, at least among older people.
I'd agree completely but this could just be due to logistical constraints of the ANAE, I took a course with Charles Boberg (one of the authors of the ANAE) and he was definitely aware of that, I vaguely recall learning from him that the Newfoundlander accent traditionally doesn't have t/d flapping which is totally unique in North America. Great class, he definitely has an incredible knack for precisely imitating accents.
It's absolutely oversimplified, someone from a small coastal town in Newfoundland does not sound at all like a person from much of the same area labeled "atlantic canadian" in Nova Scotia, or in larger cities like Fredericton or Moncton in NB. Putting basically all of NB, NS and NF as one large pink blob on the map is a drastic oversimplifiaction.
It also seems that whoever created this kind of gave up when figuring out Canadian speech patterns spanning longitude from east to west. Somebody from Kenora or Dryden or Timmins Ontario does not speak like a person from North Vancouver, BC. Vancouver region English is much closer to general west coast as it's spoken in a big city in WA, OR or California.