Answer: It is because the letters of the Hebrew language don’t change, and it is impossible to express them differently. Take any source you like that is thousands of years old and a modern book and you will see that not a single letter has changed.
It is just like a mathematical formula, if you change one symbol with another, you would not be understood, and it would also lead to nothing.
Besides, it isn’t about just another symbol, although a letter in the pure sense is a symbol. When you express your feelings through letters, you affect the world. A letter connects you to the internal system of the world, and by that you seemingly press the buttons, and do something inside the internal system.
Comment: But when we look at a book now, we don’t see or feel anything at all.
My Response: It is a multi-layered system, and even when an ordinary person looks at these letters, he still penetrates the system to a certain degree and receives some illumination. The light operates on him.
There are people who don’t understand the language at all, but during the lesson they place the book in front of them and look at it, even if they cannot follow the text, and the text impacts them.
From KabTV’s “Fundamentals of Kabbalah” 1/6/19