I find it really difficult to interact with many people with autism for extended periods of time. However, it's really not them, it's me.
I have ADHD, so I think differently. And I'm already exhausted trying to think like an NT person to get by in life - I simply can't manage to 'speak' three different languages at once.
A lot of my friends have ADHD (I didn't seek them out consciously because of their ADHD) and we have conversations that many NT people would hate. We are constantly talking about 30 different things, flitting back and forth between subjects and never finishing any one discussion there and then.
With my NT friends, I have spent my life pretending to be them, so it's instinctive to keep up with how they communicate and to adapt accordingly.
I think you can draw a little possible friendship Venn diagram with ADHD and autism in circles that don't touch, and NT right in the middle.
With people with autism, while I'm sure they also find it hard to keep up with normal conventions, again, I bet many of them have spent their lives trying to be NT (to varying degrees of success). So, in all cases, whatever type of neurodivergence, it's just easier communicating with NT people rather than different ND people.
The trouble is, the rigidity of autism clashes with my ADHD chaos. Often someone with autism will want to meet at a certain time, and if you can't make that time, you don't like them enough. Someone with ADHD will promise to make that time and mean it, but inevitably fail. We live and thrive in chaos.
(It does make me laugh every time someone on MN posts a thread about people being late and not respecting them as I do wonder how much undiagnosed neurodiversity is there...)
But just because it can be hard for people with different types of ND to be friends doesn't mean it's impossible, and it's really not a reflection on either of them. It just means that it's easier to seek out more NT friends who can adapt better to our respective quirks. We just have different needs, and we're trying really hard to survive in an NT world in our different ways.