The reason why this debate has been and is still going on, even with the evidence to the contrary, is the money trail.
The average cost of therapies for Autism is about $50,000 - $100,000 US per year for at least 2 - 3 years for those who end up being higher functioning and even more for those that are lower functioning. Health Insurance companies refuse to pay the costs calling it a mental health issue (will be interesting to see where mental health parity leads), the schools do not want to pay for it because they do not see it as a medical issue, and for those who never get the ability to survive on their own, the government is not real interested in paying for their care for the rest of their lives. I am sure that in some ways, athasma is in a similar area.
To make the situation worse, there is stress on the whole family. The parents cannot go out together because they cannot find someone to care for their kid. The other kids feel left out. There is the monetary stress. Simply put they want someone to pay.
Who better than a big bad corporation who has deep pockets. So of course, now they are going to be blamed. The lawyers pick it up for the money and the media picks it up because situations like that sell news. Even worse, if there is evidence that proves that this group is wrong, it is either ignored or there is a conspiracy. I remember a couple of months ago where we here on Slashdot where a mother and person with Autism did a blog against the whole MMR causes vaccines argument and was vigorously subpeonaed by a lawyer fighting for anti-vaccine parents. This occurred in the Dow-Corning fight with Silicone Breast implants too.
Add to the fact that in most cases, scientists cannot and will not say for 100% certainty that MMR does not cause Autism. This is because nothing is 100%. If 100 people jump out of a 3rd story window and all die, are you 100% certain that the 101st also will die when the jump out. In fact, the agent which is claimed to cause the issues has been removed from vaccines in many states in the USA and the expected drop in autism has not occurred. That should be enough proof for most people that they are looking up the wrong path.
I do not think this will die however until someone/thing comes up with a system to pay for the treatments of autism and other issues. This is all about the money.