The problem with debt is if something fails, the debt provided an unlimited risk, we want failure to have a minimum cost.
If I invest £1000 in a venture and the venture succeeds, I want maximum upside. If the £1000 investment fails, I want to get my money back without default, plus a penalty for each year that my capital goes unpaid. So my maximum risk is £1000 and the foregone interest of the debt. I think this is fair and does not punish failure