will this work??

My fellow grower told me that I should sprout my seeds in plastic cups 1/2 full of soil. Then when the seedlings reach a height of about 4 in. they should be above the rim. This is when one adds more soil filling the cup the rest of the way up.(The soil line should be about 1cm from the top part of the seedling). He told me it increases the plants strenth, increases nutrient absorbtion, and makes the main stalk extremely thick. Has anybody ever heard of this? I am just wanting to know because I am about to do this to 4, 4 in. seedlings. Thanks for any help

if your plants stretch and have a 4 inch long stem then yes that would help it grow stronger, but if you grow your plants outside in full sun or inside with ok to decent lighting they shouldn't stretch at all, and by the time they are 4 inches tall will be very bushy,with 3-5 sets of leaves. burrying a leaf underground is bad, it would mold and rot and spread to the stem. so thats my opinion, only bury your plant deaper if it has enough stem to alow this, but go only deep enough to reach the first set of leaves.