I think you and/or whoever this quote is from may be confusing the fact that the racquet and even the wrist travel downwards after the apex of the snap on every serve, albeit to varying degrees depending on the serve. But the shoulder, elbow, wrist, and racquet are always thrown upward before pronation turns them downwards after the apex.
Yes I understand this. But I've noticed many people who explain upward throwing mechanics make a serious error, and you seem to have made it yourself:
Yes, the racquet is quite literally thrown upwards.
No, this does not mean that the vector of energy imparted towards the ball is in an upwards direction.
Yet, people who explain the upward mechanics motion imply that the vector is actually imparted upwards, and that it is gravity that brings it down. This is absolute nonsense, and confuses the issue!
What's the point of worrying about the minutae here? What you tell yourself to do to help achieve the results you want and what actually happens in a real, physical sense are very rarely the same thing.
I agree that telling people to direct their energy upwards is important and useful, but when you throw in the following false statement:
"and because you direct your energy upwards, the ball is actually hit in an upward direction, and it is gravity that brings it down"
will only confuse people, and give them a wholly inaccurate model of what is actually happening.
Better to say:
"Direct your energy upwards. Throw the racquet up at the ball. Don't worry about the ball being hit towards the sky - it won't. Because of some cool wrist mechanics that you don't need to worry about, the racquet will actually hit the ball at a downward angle"
But to say that the ball is actually being hit into the freaking sky and then drops down like a stone is ridiculous.