Well, getting condescending with an abstract concept i.e. a language won't take you anywhere 😅 If it makes you sleep at night, you can leave it out, but to us it sounds better with "non" (e.g. "appena finisco ti chiamo" sounds ok, but "non appena finisco, ti chiamo" is better).
Languages have a lot of this kind of quirkiness, we could ask why on earth English uses "read" for different pronunciations, or "-ough-" for way too many sounds, but that's simply how the language works 👍
@DanJanRob no worries. When studying languages it's great to seek for the "why"s, but sometimes languages follow path that we can't understand completely, so for those occasions it's better to just follow along with what natives do 🤷♂️👍