All Autistic people share some of the same core characteristics that define autism -- key differences in neurological functioning, sensory and cognitive processing, and communication abilities that often manifest as disability. Autistic people, like all people with developmental disabilities, are at much higher risk for abuse or victimization -- sexual or otherwise -- than the general population, but that doesn't mean that Autistic people don't know about or can't have sex.
It is impossible to know what an Autistic's abilities and skills versus needs and challenges after a brief conversation either in person or in the comments thread of an internet post.
What makes Autistic people a group united by a shared diagnosis are the commonalities of all Autistic people. Other Autistic people are never taught about sex, for a variety of reasons.
A very small minority of Autistics are also savants.
Many Autistics have higher than average measured IQ, and many Autistics have measured IQ that falls right into the median, while still others have an intellectual or cognitive disability.
But plenty of Autistics do get married, have jobs, or go to college. (For those who may not regularly read my blog, ableism is like racism, ageism, or sexism, but directed toward people with disabilities.) While not every Autistic person may be able to do all or some of these things, it's very ableist to assume that no Autistic person can or that anyone who can must not be Autistic. Some Autistic people take medications for various reasons, and some do not take any medications.
You wouldn't ask a stranger if they were on medication for anything, so you shouldn't ask an Autistic person whom you don't know very well if they take medications either.
All of these things have actually been said to Autistics, children and adults, and some of them are unfortunately very common.
Some happen more often over the internet, and some happen more often in person, but they're all phrases or questions that can be incredibly hurtful.
Sometimes people who say these things are well-meaning, which can make the impact even worse.
Especially in those cases, people might not understand why these can be so offensive and hurtful, and occasionally insist that what they're saying is a compliment, even when it's not.
The ability to write a blog post says absolutely nothing about a person's needs and challenges, and how disability might affect an individual person.