It provides a materialist foundation for further analyses that would otherwise be absent. It’s extremely useful for the precise reason that it is objectively true, while demand side economic models are ideologically based.
An LTV analysis begins with such workers because they are the original contributors of surplus value that is appropriated by the ownership class.
I recommend reading about it in more detail if you’re interested, I’m not certain but I think it is addressed in Chapter 6 of Capital 1. I don’t mean to be rude but I really did have a tiring day at work and you seem to be clutching at straws a little with some of your comments.