There are many reasons to learn how to divide WWI into syllables. Separating a word like WWI into syllables is mainly to make it easier to read and pronounce. The syllable is the smallest sound unit in a word, and the separation of the WWI into syllables allows speakers to better segment and emphasize each sound unit.
Knowing how to separate WWI into syllables can be especially useful for those learning to read and write, because it helps them understand and pronounce WWI more accurately. Furthermore, separating WWI into syllables can also be useful in teaching grammar and spelling, as it allows students to more easily understand and apply the rules of accentuation and syllable division.
In the case of the word WWI, we find that when separating into syllables the resulting number of syllables is 1. With this in mind, it's much easier to learn how to pronounce WWI, as we can focus on perfecting the syllabic pronunciation before trying to pronounce WWI in full or within a sentence. Likewise, this breakdown of WWI into syllables makes it easier for us to remember how to write it.