I don't know much about landscaping fabric but I can see how a synthetic product could have harmful chemicals in it and I have definitely seen it degrade over time.
Some plants like Bermuda grass can be tough to deal with. I have seen where 2 layers of cardboard and 4 inches of wood chips wasn't enough to keep it from growing.
Maybe a chemical solution is the answer but you have to understand what is happening and how to fix the problem you create when using chemicals.