But the term you’re looking for is tunnel vision.

It refers to committing resources to interpretation of the world around a single immovable assumption.

I think they can certainly apply to any situation where the logic is flawed, so arguing that something is necessary since it’s part of another system which itself is unnecessary, is a logical fallacy

If we accept that something is a necessary component of an unnecessary system, but then use that fact to argue that the component is necessary in absolute terms, that’s a logical fallacy given that it’s not absolutely necessary if the system it’s a part of isn’t absolutely necessary

After researching I found it can be called a false necessity fallacy or false requirement fallacy