Forty hours a week seems like an awful lot of therapy, especially for a very young child. And it's no joke finding and paying for it -- unless, as is rarely the case, your local service provider or school district is willing to underwrite it. But intensive, early ABA really does seem to make an enormous difference, at least for some children.
I asked the Lovaas Institute, creators of ABA, "is it really necessary to provide so much therapy to be successful?" Here's part of their reply:
Imagine rephrasing the question as follows, “Is it really necessary for a child to attend first grade all year to be successful and pass on to second grade or can she just attend school for half the year?” Studies between 1987 and 2005 that only provided 20-25 hours of treatment to children with autism in effect reduced their schooling by half. Is it any wonder the treatment was not as successful? Read more...

I don’t really believe my son would have been able to tolerate that much therapy, although I realize that many other kids did settle in after they realized there was no way to avoid the therapy. Maybe he would have also. I didn’t really have the option then. When he was five, he went to an intensive services classroom which provided only about 15 hours a week of ABA — but I do think it made a difference. It was helpful. He is not high-functioning, and I don’t know if high-functioning kids tend to benefit more. I would imagine that my son’s rather serious retardation would limit the outcome. It’s a hard question.
This is horrifying. To put any child in a program that isn’t developmentally appropriate for ANY child as young as 2 or 3 is just crazy.
My son has autism and I never ever would have put him through that.