I've read that article by Toynbee and I don't see where Laffer has got this theory wrong?
Laffer argues that governments should maximise revenues by cutting taxation, however his curve and theory clearly demonstrates that if you cut tax too much, you will see tax revenue drop off.
He argues don't tax too little to too much, the point he was making was find the right balance to optimise tax revenues.
Laffer theory definitely doesn't argue in favour of slash and burn taxation, as advocated by the likes of Rabb, Patel and other foaming at the mouth nutters!