Our ancient sages were far more brilliant than our pea-brains could comprehend. They knew that manuscripts and written documents could be destroyed, burned, lost in time. And once they are lost, they cease to exist. Hence they came up with Shlokas. Shlokas are poems or songs which are made in a perfect meter called the Anastubha meter. Thus any addition of wrong words would destroy the meter and at once the error would be caught. And the whole text could be memorised and transmitted orally to the next generation. Thus there are no error words, nor any loss in transmission. And true scriptures, the original shlokas exist for thousands of years
Anastubha meter is a social Sanskrit meter for Shlokas which keeps the rhythm of the Shloka and turns it into a hymn.