There are still a bunch of vets that recommend the every year routine. Almost all of the distemper vaccines have a 1 year DOI (duration of immunity) listed on their inserts, so many are going with that until the inserts change. That probably isn't going to happen as it would cost large sums of money to prove efficacy through challenge testing and would result in decreased vaccine sales.
There is ample evidence that immunity lasts longer than 1 year, but in making the decision vets are taking on a greater liability going against package inserts/recommendations.
There is a statistical association between some immune mediated diseases and frequency of vaccination, but your dogs are far more likely to develop a disease that could be protected rather than one of the very rare immune mediated diseases. A huge majority of dogs have gone through life with annual vaccination and no repercussions.
We're kind of going through a similar thing with kids now. Many parents are opting not to vaccinate against measles based on fraudulent claims of an association between autism and vaccination (despite repeated repudiation by multiple people and studies in this field). As a result there is a marked increased incidence of measles in kids with deaths reported.
Sometimes it's hard to get through the hype.