Tax avoidance might be a factor sure, but can it be enough on it's own? If IT wasn't increasing the value of intellectual property, taxing it would be an economy-distorting issue. So I see the tax issue as being the cherry on the top, but not the core issue.

Tax manipulation doesn't change the fundamental value of labour, but IT does. It enables vastly more value to be created using less and less labour and materials, sometimes by many orders of magnitude. That's the game changing trend.