If you need carb parts, you can get those online, or through a channel other than Stihl. Zama carbs are not a Stihl part per se, so those parts do not have to pass through a dealer. If you need a carb , or a rebuild kit, find the number and get it through third party channels if you wish.
Other items that at unique to Stihl are not sold online, as lawboy dan stated. Yep, a real problem.... (another story for another thread).