It's not something you can disagree with, because it's a fact.
Skyrim most definitely pushed the boundaries in terms of gameplay and world design. Because of the free open-world approach that was considered such a succes, everyone and their mom has now jumped on the open-world RPG bandwagon. DA:I is open-world because of it, The Witcher 3 is open-world because of it, the next Legend of Zelda will be open-world because of it and Kingdom Come: Deliverance will be open-world because of it (and I'm sure there are many more titles that are influenced by Skyrim like that).
Skyrim sold like crazy, and that is exactly the reason why everyone is trying to mimic Bethesda's success. Regardless of what your opinion on the game is (and I have you know that we might actually agree on a lot of things, my opinion of Skyrim isn't too high either), Skyrim had a huge impact on the game industry.
Do not say anything is fact, when you are showcasing opinion. It makes you look a bit off.
First, Inquisition is not an open world, if it was, there would be seamless areas connected to each other to explore.
Second, The Legend of Zelda always had games where the world was "gated". The original Zelda, for example, was an open world game; Ocarina of Time was a "gated" style of game, where you can technically go anywhere, but you need items or need to solve puzzles in a certain order to do it, so going fully open world is not something new, it's something Nintendo hasn't done in a while basically. They even experimented with this in A Link Between Worlds, allowing players to rent the items you need to go wherever you want, instead of finding them in the proper dungeons in the proper order.
Another point...GTA III is the real impetus for the open-world craze, not Skyrim. Skyrim just happened to make a lot of money, and a lot of people like making money and are trying to copy the Skyrim "feel" in their open world. Skyrim did not, however, push too many boundaries, they simply have been doing what they have been doing since the mid 1990s.
Now here is a difference; Mass Effect allows us to have voiced protagonists in RPGs. That is a bigger impact because we now see how commonplace voiced protagonists are; hell, the ****** convo wheel is almost standard to an RPG. Plus, we have interconnected storylines and plot points to form major decisions in the narrative, which shapes the experience.
That is a direct influence to episodic games, series progression and investment, and even world building for single player games. Even Fallout is emulating that at this point.
Honestly, Skyrim just did what it always did. It finally clicked for people though which is what made it popular. That, and mods of course because PC players are crazy like that.