Outsider said:When a person who is learning Spanish asks about a particular construction, and native speakers tell that person that the construction is "incorrect", I don't see that necessarily as an attempt to stop change.
It can be simply a description of the present stage of the language, what is currently considered valid, and what is not. Only the future will tell what Spanish will turn into tomorrow, but it's useful to know what it is today.
Agreed (imagine that! )!
I just think it's also important to mention all forms of speech, whether correct or not.