It isn't a plot hole just because you don't like it. It isn't a lack of care with the lore because Durin III was alive when the rings were forged and Durin IV was alive when the War of the Ring took place. The timeline has been compressed so those events take place within a shorter span of time so Amazon can build up the same characters through out the season. Because of that compression it means that both are alive at the same time. Amazon could have chosen to go with random Dwarven kings instead but do you honestly think they wouldn't be nitpicked for not having a Durin?
- - - Updated - - -
You wouldn't have to be talking outside the context of the narrative because that same narrative sets up the One Ring to be a ruler. What is another name for a ruler? It really is as simple as that. If people can still make theories about the Two Towers which has an actual definitive answer then something that doesn't have one can have theories as well, yes? Lmao.
- - - Updated - - -
What is the name of a ruler? Lord. What is the One Ring doing? Ruling the other rings. If we are talking about just facts with out feelings and opinions then Lord of the Rings can certainly apply to the One Ring. But as you say people try and make bullshit points just like you are doing now.