Average deal size is $15m which means that the company probably has some mix of equity and debt in their capital structure. Equity can be used to cushion variance in debt servicing payments. Ultimately if you're taking on debt you're expecting that your your ROI is exceeding your debt payment. While some companies may default, an equity position may not have saved them either. Net-net, smart use of debt could generate better returns for VC as an asset class as companies will suffer less dilution and it'll drive stronger selection for companies generating positive cash flows.