i think most people who play Valheim for the first time make a large base but soon realise that this means alot of running backwards and forwards form your base especially the more you explore the map which is tedious (why people needed portals).

Most realise at some point that it is easier and less tedious to make an outpost in or near the biome to gather and refine ores then forge Weapons/armour on site only taking surplus metal back to main base (i believe this is how the devs envisioned their game, not making 1 base but many bases across the map which is why metal cant be taken through portals and why some crops only grow in some biomes)

I think that some people see the no portal run as the purest form of playing valheim a true nomad viking going where the wind blows never having a permanent home.

Each move to a new biome means taking food and resources for crafting stations, choice of base location is more important as access for ingredients for potion brewing and extra building resources is key. Having to use what that biome has to build bases with or make do, will you run out of supplies before you can get more food and gear up, trying to get a comfortable base there while fighting off the biomes enemies. Then pack everything up and move on to next challenge :)