As I explained later in the post, “Great.” looks like sarcasm. My brain interprets it as having a sarcastic tone, and thus being passive aggressive. (I am not alone in this, hence the very thing we’re commenting on.)
I get that it's a common interpretation amongst a demographic.
You might as well ask why tone of voice changes the way we interpret things
Eh, vocal changes carry actual physical changes in the sound waves which non-hearing-impaired persons can perceive, so I don't quite think it's an apt comparison. But I understand your intent in doing so.
But of course these norms aren’t as readily understood as actual tone of voice, which is why things like “/s” can be useful.
Precisely why it seems odd to me to interpret the use of the basic of punctuation whose literary meaning hasn't ever carried an absence of express indicator of emotional intent to be negative.
Again, thanks for engaging with me on it, even though I still don't get it.