Personally I find kids with autism/Aspergers tend to learn social skills better from adults who already know proper social skills. It's tough to learn social skills from children/peers who don't really understand social skills themselves whether they are nt or not.
Schools are full of horrible social skills. Bullying, teasing, swearing, fighting, fooling around, etc. Those aren't appropriate social skills. When you homeschool you can take you kids to a lot of places where they can interact with adults and learn appropriate skills.
That being said, usually when you homeschool there are still lots of opportunities to play with and have friends. My kids have lots of friends on the block still that they play with after school, there are lots of homeschool activities as well. My kids are involved in film school, swimming lessons, musicals, play dates, hs teen nights, youth group, church events, etc.
We are rarely home! *grin*