Ok, well her blog is redonculous.
First the picture used, is incorrect IMO. Your feet should NOT surpass the girth. Clearly in this picture, the riders toes are beyond the girth. Your heels should be aligned with your hips. If you can look down, and see your toes - your feet are too far ahead.
Secondly, you cannot stick a glove or something flat just below the knee's and ride around - because that teaches the rider to grip. That doesn't teach the rider to maintain a proper leg position.
Thirdly, where is the information on if the rider has a saddle that doesn't aid their position, but hinders? You can tell a rider who has poor leg position how to correct it till the cows come home, but if the saddle is not the correct saddle for the rider, no amount of struggling and work will correct it.
And, the fourth point as stated by bsms:
The stirrup leather should hang down. Gravity should naturally encourage it to do so. If your saddle fits and you have the right bend for the stirrup length, then your foot should naturally go beneath you. If it doesn't, wouldn't the problem be an unbalanced seat? (I'm in learn mode, not lecture mode here.)