Lifting the lid on cooking rice - is it such a big deal?
I am going to assume you are cooking the rice on a pot rather than in  rice cooker. If you are cooking it in the rice cooker, you wouldn't need to lift the lid to check for done-ness. However if you are cooking in a rice cooker, the lid should not be immediately lifted off after it says it is done cooking. You need to let it sit for about 5-10 minutes so the steam can continue to cook.

If you are cooking in a pot, the main reason why you do not want to lift the lid is because you want a even cooking temperature throughout. Typically when you cook rice(once again I am going to assume just plain white rice), you start the water/rice mixture by boiling it on high until it comes to a boil. I do recommend stirring it at this point. But not after covering. Then you set it to very low and cover and let it simmer for about 15-20 minute or more depending on quantity. By doing this, you can evenly cook the rice throughout so that the rice isn't too overcooked on the bottom. If you continue to lift the lid, the temperature would drop, and the top would be less cooked than the bottom. So you would need to cook it longer for the top to be cooked while the bottom is being overcooked.

In addition, the steam that is escaping is the water that you put into the rice. thus when you lift the lid, the water is escaping and will result in the rice being dryer than optimal. If you want to add more water, this will slow the cooking process on top of it already being slowed by losing temperature when you lift the lid. This will result in slower cooked rice.