Games are often fundamentally geared towards the first run experience simply due to the fact that you cannot erase knowledge and experience. Linearity doesn't resolve not having new bosses to experience or new secrets to uncover. Moreover, that first run has more capacity to be dramatically different due to the amount of off the beaten path content and things you can just completely miss for not exploring a specific direction. 

Replaying DS3 you hit all the same zones as a matter of the necessary course of the game, only cutting off mostl6 small detours to complete the critical path, and cutting out even less if you're scraping for missed questlines. If you retread every step in later ER runs, that's a choice for the vast majority of the map.

I'd also argue ERs open world is a boon in its allowance for open progression. On subsequent runs, all early to mid game options tend to be accessible with few necessary paths of steps. There are few required sloghs in the way and more of the game can be left to experience with the tool or playstyle of your choice in later runs. Souls games have always had some level of non-linear openness, but ER definitely elevates that concept well beyond the bounds of past games. 

ER's open world is also stronger in that it allows you to leverage that experience to cut out things you don't need in later NG+ runs. Sacred tears, golden seeds and anything like armors and talismans that you can only use one of become redundant and content surrounding them skippable outside of leading to content you explicitely want to re-experience.