I agree that language is fluid - always has been, always will be. People casually posting in internet forums aren't going to be overly concerned with details. Typos happen. And sometimes folks intentionally use misspellings and bad grammar to emphasize how they feel. I've been known to do just that. For instance:
"Ahmo gits me summa dat!" (I'm going to get some of that!)
However...when "lose" is consistently misspelled "loose," "their," "there," and "they're" are constantly misused, and apostrophes are used to denote plural rather than possessive, I think there's a problem. And these are just a few examples.
Centuries ago, most people probably had little or no access to standard educational resources, so they probably spent a lot of time spelling phonetically, and most likely didn't know the proper punctuation and grammar of the time. The teaching of proper spelling, grammar and punctuation was most likely available to the privileged few. Today, we have all sorts of resources at our fingertips, not the least of which is the internet. The public education system could surely be improved, but one can still learn the basics. If you hand in a report or term paper to your teacher or professor, or submit a resume to a prospective employer, he or she is not going to say, "I can easily overlook the numerous misspellings and grammatical errors due to the fact that language is fluid." Current standards still apply.
I get that this is not nearly the most pressing issue in the world, but I think being in the habit of communicating properly in print is important. Fellow TBers - what's your take on the subject?
P.S. Feel free to correct any errors in this post!