I can't help but feel like the real point the author is trying (not very successfully) to communicate is the importance of considering how other people will interpret and understand your messages. This includes content (will they understand this acronym?), but also includes how they are likely to interpret the tone of your message. Punctuation, grammar, emojis, etc. help to communicate tone -- but that doesn't lend itself to a blanket "always use punctuation" statement. Being too formal can appear cold and aloof; being too informal can appear apathetic or unkind.
It's also important to consider the range of reactions. For those who understand an acronym, they likely won't even notice; for those who don't understand it, they risk losing face and potentially looking like an idiot when they have to ask what the acronym means. The "time saved" is helpful, sure, but considering how people will respond goes beyond "how much time will they spend asking a follow-up question?" and also includes "how will they feel if they don't understand this?"
It's also important to consider the range of reactions. For those who understand an acronym, they likely won't even notice; for those who don't understand it, they risk losing face and potentially looking like an idiot when they have to ask what the acronym means. The "time saved" is helpful, sure, but considering how people will respond goes beyond "how much time will they spend asking a follow-up question?" and also includes "how will they feel if they don't understand this?"