Yes absolutely. Text casing is part of communication, by skipping it an author is saying: "I'm going to prioritise my preferences and making a statement above your understanding and clarity". The bigger the audience the more negative impact it has, and the more entitled the author appears.

Along the same lines though, txt spk to friends is a) far lower impact with the smaller audience, and b) communicates other factors such as what device you're on or how close you are to someone, so this is not me just hating on bad grammar.