If I thought it was just how they wrote on the internet (for whatever reason), I be a little less bothered, but I've read enough nurses notes and NPs notes to know that apparently many of these individuals think that they "don't have to" spell correctly or use proper grammar in clinical situations, either.
Honestly, if one is used to using proper grammar and spelling in their day to day lives, wouldn't it be unnecessarily hard to on purpose wrote poorly just for the internet's sake? Not minor things, like the occasional missed comma, that don't affect the ability to understand the sentence. But when things become unreadable...well, that's a problem.
I also have a pet peeve: people using "whom" when "who" is correct. Stop trying to write fancy! You are doing it wrong!