WW points system is essentially calorie counting. You just convert your 'calories' into their points value. Just a different way to count your food intake.
There are a million diets based on similar things - Volumetrics is another big one going around right now. Which is basically, the same thing a few years ago called Portion Control.
Read labels. That is the most important thing. If we know what we are putting in our bodies, we are aware of what it is doing to us.

A lot of the average American diet is pure junk that we tend to eat too much of.