The majority bulk of the map in Fallout games is connected while in MGSV it isn't and you're locked in certain sections on the map as well, gametrailers were one review that said what I'm saying to you. Also in your own quote:
Open world and free-roaming suggest the absence of invisible walls, and loading screens that are common in linear level designs.
Under this MGSV isn't open world due to the being no connectivity between the areas, FFXII is a clollection of areas that aren't semalessly connected and just like MGSV has to load up new areas when travelling to them which going by your own quote doesn't fit under open world. Broken promises from a developer means we can't just take their own words as gospel, I disregarded your narrative argument because it was irrelevant as narrative does not define open world, you were arguing of things to do in an openworld and chose a game that's not really open world and has a more narrow structure to it.
Comparing the narrative of Fallout and MGSV is broken, the former you obtain information as you explore and progress through the world, MGSV you selcet scripted missions and carry out the objective in the area, Fallout everything is happening while you're there in MGSV you have to select a mission to generate a lot of what you brought up and it's all not in one mission. You go in one mission to do one of the things you mentioned then go in a nother mission to do another of the other things you mention etc... This is not encouraging exploration like you claimed earlier they're just mission objectives and sub-objectives and is not even comparable to the likes of Fallout, Skyrim, The Witcher and so on where everything or the majority of things are happening for you to come across this is why I didn't acknowledge that argument.
I can point you to one of the biggest Twitich channels for MGS fans in UKnighted where they flat out said the pseudo open world aspect added nothing and was actually disappointing if you want you can follow them and when they next steeam feel free to go and ask them. I mentioned MGS3 because the roaming of large areas is in MGS3. You're comparing a game that at best is not even barebones open world to games that are full on openworld, this is why your experience with the game and using it as a basis for openworld game arguments is flawed as it's like someone someone playing double dragon then gearing their complaints about it to fighting games like SF, KOF, MK and MVC etc... The game's strength is not in open world aspects to begin with.