It would be interesting to know how many of those classes he taught and how many students, so we would have a better idea of the size of the sample he is using to make those generalizations. It would also be useful to know why most of those students were taking that course. How many genuinely loved to write, how many took the course because they thought it would be easy, and how many took the course because they had unrealistic dreams of getting rich by writing and liked the idea of being a writer much more than they liked actually writing. If most of his students fell into the last two groups, no wonder they were difficult and lazy.
But I agree that most of the things he is saying tend to be true ... most of the time. Probably the vast majority of the time. But that still leaves a lot of lives and people and situations where each of the things he says is not true.
A love of books early in life does make a big difference, and I think that most of the time it's a big advantage -- but people who discover the joys of reading later may, in some cases, appreciate books more because they notice things that readers who started earlier may not see as clearly, their perceptions blurred by familiarity. I agree that writers should have a love of books and words, but that can develop at any age. If someone tells me that they want to be a writer and I say, "What kind of books do you like to read, who are some of your favorite writers" and they say that they hardly read any fiction, then I don't think they are ready to start writing fiction yet, and I doubt they ever will be. But sometimes people's lives take an unexpected turn. The person who doesn't read fiction now may fall off a ladder and break several bones tomorrow, ending up in a hospital bed for several months, and having nothing much else to do and bored out of their minds, read a few books that someone dropped off ... and discover, by gum, that they love reading after all.
I don't know that it matters how early you get serious about your writing. A lot of people don't become what I would consider truly serious about their writing until later in life. I didn't start applying myself to my writing with any sort of dedication until I was 29. That doesn't mean that I never did any writing up to that point, and I find that a lot of people who say they didn't start writing until they were in their thirties or forties actually did write stories now and then as children. I know that I did, and I was always making up stories in my head, to entertain myself. I think that maybe the stories you tell yourself may be as important as the ones you write down. Those early stories don't have much to do with language (later they may, because I find myself editing even my daydreams these days, which makes them a lot less entertaining) but I think they can aid you in developing plots and perhaps characterization. There are a lot of things you can do to prepare yourself to become a writer, things that don't necessarily involve putting words on the screen or on paper.
I was a member of a writers group at a local bookstore, and I was amazed by the number of members who were writing about themselves, or (as they wanted people to know) fiction that was highly autobiographical. I don't know whether this was ego, therapy, or because they had been told so many times "Write what you know." Sometimes our own lives are the things we understand the least about, but I can see young people interpreting "write what you know" to mean "write your memoirs." I have met a lot of people who, on finding that I am a writer, blithely come out with, "I've had an interesting life, and I think it would make a great book if I ever have the time to write it." It's boring to hear that all the time, but I don't really think it's that different then any of the other daydreams people have and never really mean to go through with.
And I do believe that if there is something you desperately want to write, that is demanding that you write it, you will find the time. You will arrange your priorities so that you have the time. Nothing that happens will stop you from finding the time. BUT there are a lot of thing that can happen, there can be a lot of things that you have to do, that can dry up your creativity so that finding the time no longer becomes a big priority. Plugging away at writing when you feel no engagement with what you are doing, just because you've been told that that is what you have to do if you want to become a writer, when you are tired and you are stressed and there are some responsibilities you cannot shirk, that's a good way to take all the joy out of writing, and I don't think it gets you any further ahead.
On the other hand, if it's a school assignment, you have presumably set aside enough time to do the course work when you signed up, and having committed yourself to do the work you ought to do it -- or, if your life really has become that complicated that you can't do it, drop the course and stop wasting the teacher's time. I can see why a teacher would become so tired of hearing excuses from bright-eyed students (clearly not stressed by some major life crisis or dying of some almost immediately fatal disease), who really do have the time, but have simply not been interested enough to arrange their priorities, that he would become jaded and cynical and disinclined to accept any excuse as valid. It would be understandable, but he would still be wrong, because sometimes there are valid excuses.
It's also possible that he is not a very inspiring teacher. Some teachers are so brilliant at what they do, they can make students enthusiastic about reading assignments they would have otherwise hated. Some teachers are so boring they can make students hate a book they would otherwise love. I suspect the teacher who wrote the article is somewhere in between -- no better nor worse than the majority of writing teachers.
