Debt can be useful to quickly get capital to grow a business. The problem is that everyone is competing to grow their business faster and so the amount of debt steadily climbs faster and faster than being able to pay the interest. New businesses who gather debt in a more controlled way will look like they aren't growing as fast (if loans were the primary source of funding) and they are quickly left for the companies that grow fast. Luckily, VCs take responsibility with their investments and make it possible for a new business to not need to go into crazy amounts of debt.

Eventually, so much debt will be accumulated that companies will not be able to pay off the interest and the bubble pops. If everyone is always in debt, there will always be a periodic crash.