I don't see this thing described as "Linear Algebra". I see it described as "Linear algebra for game developers". To me that's two rather different things.
I think it's elementary vectors for game developers.
That's not to put it down, it's just to point out that for 20 years I've heard people saying that they want to learn Linear Algebra because it's needed in games programming, and this is the first time I've seen that perhaps they're talking about something completely different from what think of as Linear Algebra.
In my world (I'm not a mathematician) vector geometry is a subset of linear algebra. Consulting Wikipedia doesn't tell me otherwise:
Linear algebra has a concrete representation in analytic geometry ...
In classical mathematics, analytic geometry, also known as coordinate geometry, or Cartesian geometry, is the study of geometry using a coordinate system and the principles of algebra and analysis.
Regarding another comment of yours it also said:
Thus matrix theory is often considered as a part of linear algebra.
I guess the point is that these are parts of a field that is significantly larger and deeper than just these parts.
Vector Geometry is a part of Linear Algebra, it's just not a very big part, just as arithmetic is not a very big part of calculus.
Matrix theory is a much bigger chunk, but the article submitted doesn't go into matrix theory, it just uses a piddling bit of a small amount of using matrices.
And these are valid questions - I don't know why someone down-voted you, and I've upvoted you for asking.
