You can have the experience without it too, just sit there for a long time and follow the instruction you shared. Yes keeping the rule in your head is a thing to fixate on, but there's a little trick.
You see people spin balls or beads in their hands, or sometimes do a little puzzle in their mind, and claim it aids with meditation. Well, sometimes a small repetitive thing to focus on can be just as good as pure silence. This is the basis of mantras. If you do the same thing over and over and over and over it's the same unchanging rhythm as the background silence you're trying to achieve. It's only when we have all these decisions dragging us every which way that it's not possible to fall into the meditative state.
So what is it - the "state" - it's basically when you forget you're there. The longer, the more psychedelic of an experience that is. You've probably already achieved it sitting bored in class, or staring off while tired. That's it.
You can become better at forgetting yourself and "slipping into it" (or rather out of mental thoughts and into the abyss of relaxing nothingness) on demand, and get better at doing it for longer, or you can use inebrients to aid in the process.
Sometimes when you come to - you had basically a dream. That can feel profound enough for some to build a religion around this kind of thing.
It’s a bit tricky because sometimes you get caught focusing on being the observer and letting sensations pass. It’s a more subtle thought but as you practice those subtle sensations become more apparent. It’s a useful sensation in the beginning to let the more “coarse” sensations and feelings go but eventually you need to let that go too.