I certainly agree. It's not at all unusual for students in my sophomore/junior-level classes to tell me that they've never taken an essay exam, or written a 10-page paper, before.
My wife, a high school social studies teacher, would cry out that it's not fair to blame the teachers, and I agree with her - up to a point. But the English teachers in her school think teaching grammar or syntax is beneath their dignity. If they don't teach the kids to write, who will?
It's extremely unusual for me to get an undergraduate student who can write at what I'd call eighth-grade level. Some of them meet the definition of functional illiteracy. The grad students face stiff competition to get in; their writing is generally satisfactory, and sometimes downright good.
I think another big factor is that young people don't READ as much as they used to. I learned as much about writing from C.S. Forester, Arthur Conan Doyle, Nicholas Monsarrat, and several dozen other novelists and non-fiction authors as I did from any of my English teachers. When my stepson graduated from high school, in 1997, he swore he'd never read another book as long as he lived. This from a kid who'd been raised by two professional educators, in a house overflowing with books. Seventeen years later, so far as I know, he's kept his vow.
But (I always tell myself) then there's Harry Potter. As far as I'm concerned, J.K. Rowling deserves some sort of medal for convincing millions of kids that reading is cool - and fun. I like to think the writing skills of the next generation of college freshmen will be at least a bit better.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.