I'm not autistic but I'm blunt. I do it for a few reasons: 1. It's important, 2. It saves time, 3. It gets to the point, 4. I'm usually aggravated about something, 5. Some people like to dance around conversations, 6. I'm older now, so I don't suffer fools lightly, 7. It usually snaps people to attention instead of some half thought out reply.

I used to try to be tactful with everything I would say, but that ended up in a 4 hour discussion / argument with someone who was digging in their heels about something they were wrong about. Huge waste of time and energy. It would blow a whole day.

When someone is being blunt with me, I take the time to make sure my response is clear and concise. It certainly has it's advantages. I try to keep the swears to a minimum. I'm not a drill sergeant, but I definitely make my point clearly and forcefully.

FWIW, I save the bluntness for important stuff.