As phases go, your baby’s ‘throwing everything on the ground’ phase is considerably less adorable than her discovery of intentional smiling, though it probably ranks at around the same level of not-entirely-adorable as the separation anxiety phase. It's not fun to deal with for you, most of the time, but there's a certain amount of cuteness nestled somewhere in her honest amusement and wonder as her favorite toy goes flying all the way across the room. Again.
That’s because, by and large, children from around a little under a year old to a little older than a year don’t throw things to express anger or frustration, or to try to make you angry. Instead, these throwing-phases generally happen because they’ve just mastered the art of doing it, the same way when they learn a new sound or word, that sound is suddenly all over your home. If your baby has decided throwing things is her jam now, she has probably just mastered the fine art of grasping-flinging-releasing objects, and through that skill, she has discovered gravity, and is now testing it out to make sure it always works.
Beyond that, there’s another reason why your baby loves to watch things fly so much, and it connects back to separation anxiety - your baby is learning about object permanence, and the way objects keep existing even after they’re thrown. These two ideas - object permanence and and gravity - won’t be new to your baby forever. Before too long, she will take them for granted as much as the rest of us do.
Knowing why your baby does the things she does may not be quite enough - with habits like this, the question often changes from “why does she throw things?" to “okay, now how can I get her to stop?”
There are a couple of schools of thought about how to answer this question, the first of which is to wait it out. It’s a phase, and it will pass on its own. The second sees this phase as more of a teaching opportunity - stop giving your baby back the things she throws, because throwing things makes them go away. A thrown plate means the end of a meal, a thrown toy goes into a closet for a little while. If you choose to go this route, whether you choose to try to teach her to throw more appropriate things instead, like foam balls or soft toys, or go in a harsher direction and assign short time-outs after larger throwing episodes, the important thing is to be consistent, and not to respond too dramatically. your baby is learning cause and effect better and better every day, and if she learns she can make you freak out by throwing things, she may start to use that in situations where she feels ignored.