A stands for Asexual, Aromantic, and Agender (NOT ally)
And the I stands for Intersex
And look, nobody is asking you to have a in-depth understanding of every single sexuality in the world. Many microlabels are just there to make the person using it feel good. I don't expect the average person to know or understand what "Oriented DemiAro Ace" means. But I know what it means, and it's comforting to have words to describe how I feel.
Most of the time, you'll only need to know the things in the acronym, more common terms. If someone has something more complex, they can share with you what that means to them.
I'm going to say, I dislike your wording of "has to be so many," there isn't a checklist. There isn't anyone keeping score. There doesn't "Have to be" anything. People don't need a reason to be the way that they are, to just... exist. "Forced Diversity" isn't real. Humans are simply really diverse.
I hope this was helpful in some way! I love you 💜💜💜