High aspect foils develop more lift for their size than low aspect foils.
I'm going to suggest modifying this statement a little. It's not that high aspect ratio foils produce more lift (for a given amount of area), they create less induced drag. Here's a bit from North Sails:
Another factor that must be considered is induced drag. This is the drag that a wing generates when it creates lift. Over most of a wing, the low pressure above the wing is kept isolated from the higher pressure underneath by the physical presence of the wing. At the tip of a wing, where the wing ends, there is nothing preventing air from flowing around the wing tip from the high pressure beneath to the lower pressure above. This results in the standard tip vortex that is often seen spinning off the tips of airplane wings and flaps. When the flow takes this alternate path around the tip instead of over the airfoil surface, energy is expended that does not develop lift, but does cause drag. This is called induced drag and it increases exponentially with lift, so a wing, such as a sail, that is producing substantial lift, experiences much more induced drag than a wing that is producing a lesser amount of lift.
The most effective way to minimize induced drag is to increase span, as induced drag is inversely proportional to the span squared. Highly efficient airplanes like gliders have very high span for the amount of lift they are producing. Winglets are a way to create the effect of higher span without actually increasing the physical span. They are useful when there is an artificial constraint on wingspan (like a draft limitation on a keel).
This article was using an airplane wing as an example, so for a given wing area, increasing the span increases the aspect ratio.
Often boats are offered with a regular rig, or a high aspect ratio (aka tall) rig. The high aspect ratio rig will point better, since sailing to weather is where the maximum lift is being generated by the sails and lowering the induced drag lets the boat go faster.
On the other hand, for downwind sailing you want the sails to generate lots of drag, because now the drag is powering the boat. So the high aspect ratio rig with its lower induced drag is at a disadvantage here.
A higher aspect ratio rig also puts the center of effort higher in the air so will tend to heel the boat more, or require more ballast to compensate. The taller rig, on the other hand, can catch higher speed wind further up.
Like everything else, selecting rig aspect ratio is a compromise.