At some point a set of fairly strict rules is important for a written language

Given that English has become the lingua franca without having a strict set of rules, reality would say otherwise. If a strict set of rules was that important then French would be the most commonly used language.

Over-use of exclamation points is another poor habit, since they can mark something that's important regardless of it being a positive or negative. With quoted speech it could be something that's either angry or joyful. Using them to convey a non-threatening tone shouldn't be required. I get that it is in some cases, and I belive that indicates a problem with our overall literacy and a renewed misogyny in the workplace.

You realize that its just you who's having problems? You are claiming that other people have literacy problems, when they communicate with each other just fine, and it's you who are struggling to communicate effectively. They are not having problems with being misinterpreted, just you are.

Whether this is a result of the medium of communication or a decline in literacy is up for debate, but word choice and context should do the bulk of conveying tone and relying on punctuation for that purpose understandably looks like an indicator of poor literacy.

No, people insist on strict rules so that they don't have to change or learn new things, and can blame other people when they communicate poorly. The English language constantly changes, and authors constantly break the "rules" that your elementary school teacher taught you to effectively communicate ideas. That has literally always been the case, from Shakespeare, through Cormack McCarthy, to the past several decades of online communication.