It's not really uncommon to see "no smoking on the patio" or "no smoking within 100 feet of this door" signs. And some states have legalized smoking cannabis, except outdoors.
I've seen such limits imposed on private property, but as far as I know there aren't any laws (specifically for cigarette smoke) that extreme.
Don't get me wrong, I'm not a smoker and never have been. I like these laws. I'm just being a bit pedantic. There has been a general trend of restricting smoking and I think that trend has continued outdoors. It used to be that you could smoke anywhere, then businesses started creating indoor smoking sections. Then indoor smoking sections were banned and smokers moved to the outdoor seating. Then smoking outside near exterior doors was banned, in a way that effectively banned smoking at many restaurants entirely. Beyond this, in some places like NYC you have smoking bans in public parks and beaches as well, regardless of how far you are from any exterior door. (To be clear, I support these bans because cigarette smokers are notorious for their litter.)
And in the case of cannabis the restrictions are even more severe. In Washington you cannot smoke cannabis in view of the general public or in most buildings (except residential, although many apartment buildings have smoking bans too.) California is more permissive, but even they enforce a 1000(!) foot smoking ban around schools and youth centers.
That's why smoking is allowed outdoors.