Neither Elden Ring or BOTW pioneered anything in open world games. They just happen to be the first open world game a lot of people paid attention to because it's part of their favorite series and each series has hyper fans to the point you can't levy any criticisms or else they go ballistic. I don't feel like either game did open world particularly well either. In fact, their implementations have actually made their respective series worse.
Elden Ring did have some very cool places you could visit, but the overworld was boring because there was nothing particularly unique about going to some new area. I remember first coming to the place where it was stormy and I thought it was really cool, but the storms didn't have any real effect. Each new zone pretty much just felt like a graphical skin and you could see each zone had the same basic formula over and over. They might have had a gaol, a couple of ruins, an underground dungeon or two. I didn't really feel like I was doing anything unique coming to a new area.
Open world in these games also removed the tension and the focus. In Dark Souls, there was constant tension because you were in guided environments and you couldn't easy just run around the enemy like you could in Elden Ring. The best part of Elden Ring was actually when you went to the old Dark Souls-esque like castles or tightly crafted dungeons. In BOTW, open world means you could go anything, but what are you really 'doing new'? The thing a lot of Zelda fans actually really loved about Zelda was removed, which was going to a new zone, finding a new item, and that item giving you the ability to go somewhere you couldn't before. Now, you pretty much are free to go anywhere early on and you're just exploring for hearts and stamina upgrades.
Bethesda and even Ubisoft have been doing open world for much longer and better. Rockstar as well... and that's probably because they created series that were meant for open world. What makes open world interesting is actually being able to interact with the world and the people in unique ways. For example, you go steal in a shop and then people try to fight you or guards come after you. Maybe you can buy your own house... in some of the Elder Scroll games you could do things like turn into vampires or werewolves. You could craft your character however you want.
There's also no interesting 'random events' in the Elden Rings or BOTW, which is one of the things that made GTA so interesting. In GTA you might just see some utterly random, chaotic event such as a plane crashing into something random.
With BOTW or Elden Ring, they don't do anything with open world that actually makes the open world good unless you just like aimlessly exploring. In fact, they deescalate a lot of the tension since you can just run away from a lot of the threats. The world doesn't feel vibrant and like you're actually a part of it due to no real npc interaction. They take the worst part of open world, which is the huge periods where you're doing nothing in particular and you're just travelling around. Almost feels like those road trips with your parents when you were a kid and just looking at the 50th bale of hay.