So is "backcountry". Once upon a time there was just country.
I wonder if someone could refer me to some of this marketing of the sidecountry that people keep referring to, because I haven't seen any such marketing from any of the areas around me with an open boundary. ...
Well, I think often it comes up more from stakeholders in the communities versus the resorts themselves. http://blog.paintedbuffaloinn.com/tag/side-country/ but, check this blog, for instance, and it's hardly encouraging irresponsible behavior. Sidecountry is a descriptive, economical term for the subject of the blog, but not one that would cause anyone to get crazy because they heard the term.
Jackson as an example also has a lot of stakeholders that rightly promote the world-class alpinism that exists there. They are totally correct to do so, and using the term alpinism doesn't encourage anyone to take the climbing there lightly. The large numbers of people in the mountains there, and the culture of fast and light and running things out, does cause some climbers every year to get in trouble in multiple ways, but you could come up with some artificial term for the alpine climbing there and you'll still have all the same issues with hikers and climbers as you do now.