Normal people are extremely sensitive to deviations from social norms. There's even a word for it, "coolness" and more modern derivatives. Human social interactions are extremely complex, both verbal and otherwise, and people will subconsciously become uncomfortable or disinterested when people deviate too far from patterns.

The weird kids get bullied because they are legitimately weird. But pretending to be normal is difficult and tiring and inevitably you say or do enough unusual stuff that you give off weird "vibes".

And what we call "bad vibes" are often just people picking up subconsciously on subtle abnormal behaviors. I doubt that 90% of the population has actually considered any of this from an introspective perspective. Asperger's is simultaneously obvious and invisible. And doubly difficult because the rules we are supposed to follow are abstract and unspoken, exactly the kind of ideas with which autism makes people struggle.