My first question to you is, why do you have the knee-jerk reaction that talk of oneness with the universe is bullshit? Is it just because, perhaps, you are unfamiliar with the very real traditions and schools of thought that have believed this? I grant you that in the mainstream society of the West it is not exactly received doctrine, but is that a good reason to say it's bullshit?
Let's segue from that into a related critique, which you seem to be implicitly making. It may be true that everything is unified, but it isn't a useful fact. Division is useful, unity is a dead-end. (Aside: this is similar to the equally-flawed critique of skepticism [the idea that nothing is knowable] on the basis that, while it is true, it is not useful. But that can be saved for later).
However it is not true that it is not useful. The examples are so countless that I almost am not sure where to begin. I'll just attempt an off-the-cuff list. Family disputes? Better to think of the oneness than the difference. Scientific inquiry? Better to understand the working of the whole system than to try to understand one of its constituent parts (I'm sure anyone who has taken a 101 class in any department has been taken aback by how many other departments' fields are interrelated to the subject. Creative writing, art, anthropology, biology, sociology, psychology, neurology, physics, mathematics, engineering, economics... perhaps there not fields, but just one Field?). Business: if you are a restaurant in a tourist town and you are not paying attention to the various professional conventions in town, the global economic climate, the Farm Bill, Obamacare, the personal lives of your employees, and on and on, you will not run a very successful restaurant.
I'll just stop there. You can name literally anything - a holistic view, if lost, will cause the enterprise to suffer. Your argument of course is perhaps along the lines of "jack of trades, master of none." This of course is true, no one can know everything, pay attention to everything, or encompass everything. But it is true everywhere, no matter how focused you try to be. Say you corner yourself into something very specific - screwing on toothpaste caps all day. There is a certain technique to that, different things to try to do it better - there is no end to the innovation you can attempt, and no end to the background information about your job (mechanics of your hand, purpose of toothpaste, cost of plastic, labor laws, and that perennial interpersonal relations). Again, on and on. Jack of all trades, master of none is true. But the fact is this is not a conditional statement, it is s descriptive statement of all our circumstances. All of us whether we like it or not are jacks of all trades, and masters of none. It's a birthright. We live in the universe. It's fact that can't be escaped.
You seem to be implying that if I had my way I would do away with distinction and difference entirely. Maybe I would, but I can't. So, abstract away, but if in the course of your abstraction you become forgetful of the truth that your abstraction is *just that*, then it will cease to be useful and become harmful. Take money for example. A great invention. Very good abstraction of value, that one is. It's hard to argue about how useful it is. We all use it.
And yet, when this abstraction becomes more than an abstraction, and crowds out everything else, and becomes your entire universe, we all know what happens. It becomes "the one who dies with the most dollar points wins." That's not a game that's very fun to play, as it turns out.
What else do we have here... ah, the effect observers have on the world. I don't deny it all. It's integral. We, the observers, are inseparable from the world just as everything else is inseparable from it. So I don't know what you mean by not allowing for that. "Real numbers" aren't *really* real, as we have discussed in weeks past, but they are real in the sense that you and I think about them and talk about them and make decisions based on them. Putin is an "eliminative materialist", but I am not, not at all in fact. Ideas are physical realities, even wrong ideas.