Every generation speaks their language at least a little differently from their parents. Their parents tell them that they're butchering the language, but the children respond by saying that their parents are old and stuck in the past. And, as usual, those children grow up and they continuously speak their version of the language. And when these now-adults raise their own dhildren, the cycle will repeat itself.
The point here is that people hold onto their language more securely than most any tangible objects. And I am no exception. I understand the English language to be a certain way. If people start using it in different, new ways, it feels like they're butchering my language.
This is where the true test of a liberal grammarian comes in. When people use English different than what you're used to, what will your response be? Will you call them stupid or ignorant? Will you say nothing? Will you tell them it's cool or interesting?
It can be difficult to let some things go, but you must. You must accept that language is alive, that it is always changing, and that it will eventually change into a form that you personally don't like. But if you can accept those things and keep going on with your day, then you, too, could be a liberal grammarian.