In the beta, I found a couple game breaking glitches by attempting to clip through areas. Central shroud has a cave (I think by the velociraptor camp), and if you jumped on a specific rock, you could fall through the map. Simply put, most inaccessible spots aren't complete, and will create texture problems/clipping errors. While I agree there are spots that shouldn't have walls, this is an easy way for developers to keep players from accessing glitches.