For those who don't have the patience to read more on this topic, the key argument is that debt creates perverse incentives. If you follow Basel II or III regulations, you will know how hard it has been for the regulators to convince the banks to increase their tier-1 capital. The banks are happy to pile on more debt rather than raise more equity capital (the purest form of capital) as debt is cheaper and comes with nice tax benefits. The financial crisis of 2008 was exacerbated because of leverage (another way of saying lots of debt).
While this can certainly reduce leverage in the banking sector, the author raises the question of start-ups vs. big companies. Big companies have massive balance sheets and will generally be able to borrow at much better rates whether or not there is tax incentive. If an up and coming start-up is amazing, I am sure there will be 100s of equity investors who will be willing to throw money at it. I wouldn't worry about this impacting them.
That said, this will not fly in the US. So much for logical reasoning.