ranking and sort by ranking

Look at this idea param tags.
Both are fairly easy to implement. You create integer ranking (-n to n or 0 to n) for note or tag. Searching and sorting those tags/notes is easy.
n could easily become stars, icons, font size, color, bla...


To be quite honest intuitively I 'know' this is good idea. But still don't see why or how this could be used.
Maybe for sorting many similar but slightly different tags. Like programming versions or recipe for cake... Chocolate_Cake:1, Chocolate_Cake:38, Chocolate_Cake:100
These are all cakes, but you are testing different ingredients, making slight adjustments...