Of course, you can.
That first moment of gut feeling is outside the control of your consciousness, but after that, it's a choice.
You can tell yourself, and persuade yourself, that you don't know the why the other person ended a sentence with a period. Because, the fact is, you don't.
Not to mention that an ending period is quite commonly added by dictation software, so it's not even certain that the other person added it by choice.
Furthermore, the myriad of social cues usually emerge in a whole package. You get to see a whole face, or a whole body, with the words, said with human voice. That's significantly more data than the presence of a period.
If my boss chucks an ellipsis at the end of the message, does that mean he wants me to....
Answer an implied question?
Wait for him to keep writing more information?
That he wants me to justify what he has just said?
It is not a choice as you argue, to interpret meaning behind ambiguous communication, and have effective communication. I cannot ignore implied tone, because I 'don't have 100% certainty of their intention'
And that's where things get difficult - at least in non-interactive environments. I've become very wary of the thousands of slight misinterpretations that my email messages might allow, and tend to rewrite most sentences once or twice to make the wording as unmistakable as possible (usually in a cycle of "how could this sentence be interpreted uncharitably?" -> fix it up).
With increasing daily email volumes I've had to tone that practice down (at least for less delicate messages) to get anything done at all. But you never really know how something was perceived unless it went really wrong.
That's the thing - you almost never do.
> How you interpret those is absolutely a choice
The crux of the problem here is putting that choice on the reader instead of leaving them without one. Communicating emotion in text solves this issue of interpretation.
I am really curious how this evolved, and how I missed it being something people think. My biases tend to lean towards viewing people who don't use punctuation and capitalization as being less professional. I couldn't care less in something like a random chat in discord. But for Slack, as a work tool, I prefer to stay "professional".
I wonder what other seemingly unspoken biases are out there? Especially in a time where we are spending much more time in text instead of in person.
A lot of it has to be context. If I'm talking to someone new, I'm going to try very hard to read very little into the text they've sent me. If it's a message from my partner -- yeah, every aspect of that message can communicate something to me. And in that latter case, a period on a short statement is a warning sign equivalent to passive-aggressive "I'm fine."
Another thought is it literally changes how I read a sentence. Considering "I'm fine." vs "I'm fine" vs "I'm fine...", the first ends abruptly and is cut off. The second ends more gently and naturally. And the last trails off implying...something depending on the person and context. Consider poetry. No punctuation, a comma, a dash, a semi-colon, or a period each imply a type of pause (or lack of pause) at that moment in the words. And in poetry, that can mean everything.
Same here.
At the end, though, you're still making a judgement about someone with very little information and you have a choice not to do that.
In communication, your opinion of how something will be interpreted is far less important than opinions of the people doing the interpretation. You can stand firm in believing that adding the period doesn't make your message more hostile, but that won't change how your readers feel.