This is a trend that continues with modern organisations such as Google who do also not set annual goals.
When asked in the same study why these people and organisations do not set goals the response was simple.
"Defining goals defines your limitations"
As an example picture a 4 hour marathon runner who's goal it is to run a sub 3:30 marathon. They work out what they need to do - train to that specific pace and come race day run a 3:29. Goal Met.
Now imagine a 4 hour marathon runner who commits each week to followed a balance program of muscular endurance, weights, track work. Each week they meet this commitment - a commitment to continuously improve. Come race day they run 3:19.
Imagine if, for Runner 1, a 3:30 marathon was never realistic based on time till the event, training time etc ? Had they focussed on improvement over the goal they may have run 3:39 which is still a huge PB. Instead they 'miss' their goal and are disappointed or worse still are injured trying to push for an unrealistic goal and cant run the marathon at all.
The same is common for people trying to lose weight. They set a goal instead of focussing each day on eating smart and exercising properly. For weight loss the issue also can be that a long terms goal is hard to be motivated for and 'slip ups' in nutrition are ok as they have 'months' left..
In Googles case they dont set corporate goals as it decreases their agility - the ability to respond to what the market is doing (which is often outside their control anyway).
There have been lots of studies on what makes successful people successful such as Stephen Coveys Seven Habits of Highly Successful People. Things like single mindedness, focus, total commitment to a goal etc. Not surprisingly you dont see many books on what makes abject failures unsuccessful but in some studies that have been conducted it has been found that these people actually execute the same habits. Single Mindedness, total commitment to a goal etc can make the person oblivious to 'reality', unable to deal with changes to their market or environment.
So rather than defining your own limitation focus on continual improvement and commit to each day doing something that makes you 1% better than yesterday. In 68 days you will be 100% better than you were yesterday.