Does simply having these rules means that we are all going to follow them? - Just like rules of anything, there are always going to be those who bend them or break them. I am going to focus on the English language as a case study to try and demonstrate this point. I think that now more than any other previous time, people are breaking the "rules" of written and spoken language. Rules of syntax, are constantly broken, both in an obvious and subtle way. In our pop culture, whether its contemporary rap songs, which have drastically increased in popularity, or whether its in movies and other interactions of our daily lives that would have an impact in developing our language; these "rules" are constantly being broken. For example, one of today's popular rap artists says in one of his songs : "Look at what I done; look at where I be." The phrase contradicts the language's grammar rules in terms of tenses, and yet, it is used and more importantly, its intent is understood by others. Especially teenagers, and especially online, they often purposely "mis-spell" words whether its for efficiency or because its just the thing to do...such as spelling "you" as u instead of y o u. There are also a lot of subtle, perhaps unintentional mistakes that lots of people from different age groups make. For example, most people say things such as "dispute about...." when it should technically be dispute over; also, most people say " if i was (bla)" when it should technically be if I were. "it is me" is also grammatically incorrect, it should be....it is I. These are just a few of many many examples that demonstrate the fact that we break the rules of language all the time.
So if we break these rules so much, why do we still have them? The thing is, that this set of rules needs to be established as starting point. Language needs to be unified in some way. It cannot simply be haphazard. There needs to be guidelines that people can follow, so as to ease communication. I think using an analogy would perfectly demonstrate my point:
The painting above is one of Picasso's. Many people would not guess that it is since he is more famous for his cubist style paintings. The thing is, one needs to master the rules before one can break them. Picasso had to practice conventional art and perfect it before he could go on to his more creative, "rule breaking" ideas of what art is. I think this is the case with language to a large extent. Otherwise, people would not understand each other. If i did not even know teh word "you"....i would not know that "u" meant you in the first place. So, when people have a good understanding of the language, and its rules, they can break them; but still have the ability to communicate and understand each other, therefore still maintaining the main purpose of its creation.
It is important to mention, that this is to some extent a generalization. Some people break the rules of language simply because they do not know them, or did not learn them. An example would be someone who picked up a language from the streets, from people who do not know the rules themselves. However, I think the fact that everyone else knows these rules, also gives these people the ability to break them, simply due to the fact that they would be understood.
Here is one of Picasso's more famous & unique paintings:
