The primary use of these rules, in my experience, is to prevent the common usage from changing. You certainly don't do a good job teaching language by asking pe

The primary use of these rules, in my experience, is to prevent the common usage from changing. You certainly don't do a good job teaching language by asking people to memorize formal rules. You also aren't going to make a computer understand natural language by writing down formal rules. So why do it? To make observations? Observations don't need formalization; just provide good statistics.