Context: The parts of something written or spoken that immediately precede and follow a word or passage and clarify its meaning.
Most people read in a linear fashion, one post at a time. Archangelspiv ended his post without a definition of what RNG. While *I* knew what he was referencing, someone who does not could be confused.
The point is using acronyns without spelling them out first can lead to confusion. Taking a few seconds to type out the words Random Number Generator, won't hurt you. In fact, spelling it out will only lead to more clear and concise communication.