High rates of corporate debt are misleading. We've had a decade of essentially zero or near-zero interest rates. We've also had companies that generate profits on an almost unprecedented scale be able to (legally) transfer IP offshore and essentially engage in IP licensing as a form of transfer pricing (which is otherwise illegal).

So you have a bunch of people who would rather borrow money at near-zero rates than repatriate profits that they'd then have to pay taxes on. This is just deferring tax debt indefinitely. Worst case scenario for the tech companies at least is that they need to repatriate some of their mountains of cash (and possibly downsize to reduce costs).

I don't know what fraction of corporate debt this covers but given the size of the tech companies now, I'd be surprised if it wasn't a significant chunk.