I spend too much time on the internet. I would strongly argue that using the same style/level of English (punctuation, capitalization, grammar) that a seven year old knows is far more communicative and understandable than using incorrect punctuation and worrying if a full stop means someone is angry.

Perhaps people should just read the content of the message and stop worrying about the set-dressing. "They capitalized, they must be a nerd", "she ended that will a full stop, she must be mad!".