This ought to drive the scholars nuts:
lift is generated anytime the pressure is different from bottom to top of wing

no theories needed here .
more difference - more lift
size of lifting thing makes a big difference
why
air is lazy - it takes path of least resistance
just like students --------
if the air can go around the lifting thing -instead of over/under it (remember- easiest path) lift is reduced or is nonexistant. the smaller the lift thing - the easier it is for the air to simply move around -away (compress a little if that is easier ).
so - a great big piece of cardboard 10ft x10ft moved slowly- will move a LOT of air -a big pressure difference as the air can't get around it - easily stand a sheet on edge - let it drop - you will see.
But take a little piece-it drops fast - the air can movearound it much more easily
don't get caught up in airfoil theories - all of th millions of foils are simply shapes wich are more efficient under set conditions
my answer won't win you a score on a test but if you actually do some flying models -in widely varying sizes -it will allquickly become apparant to you.
in a nutshell as the lifting thing gets smaller and less capable of directing flow-- it will lift/carry/ support
LESS weight disporportionately-- the curve steepens downward
given two wings both 3-1 aspect ratio
the one at 400 squares and 6 ounces to the foot loading will seem to fly much the same as one 2000 sq inches at 30 ounces to the ft loading
In this example - 1/5 the area has about 1/5 the wing loading