because your swing doesnt necessarily translate to power.when you swing your racket, the racket head speed you generate also contributes to topspin which is required to keep the ball down. you cant just rely on gravity to bring the ball down into the court right? so you hit over the ball to generate topspin to ensure that the ball stays in no matter how fast you swing.
with that in mind, a racket that's lighter in weight is more unstable to an equivalent racket that weighs more. you want a racket that can withstand the speed and spin of the ball. if you play against a player that hits huge shots but you have a lighter racket, it's harder to return that shot because your racket is less likely to be able to withstand and return the energy back into your own shot. since you're new, i wouldnt focus too much on swingweight or static weight. if you can find a racket that's around 11.0-11.5 oz with a SW of 310-325, you'll be good for a while.