What evils would that be? ...and what does it have to do with permadeath and 'no portals'. Streamers do 'no portals' and permadeath to increase the challenge and to entertain. Most people do not play with these restrictions.

Doing a main base is a whole other matter. It's done because, I assume, most people play the game unmodded and without cheats. It's more efficient and easy to do one main base and several surrounding outposts, as you explore. Later in game the main base can be moved or gain another 'main base'. It's just about grinding enough resources for duplicate structures, furnitures and tools in the end.