Why is that? One possible answer is that the eurozone is hopelessly overburdened with debt. It's not only government debt (whose relative size is comparable to the USA). Bank loans to the private sector are no less important.
European corporations have been drowning in debt. As European bourses have been underdeveloped, bank lending has been almost the sole source of financing (other than retained earnings.) The level of the debt outstanding is very high. There's no more room for growth. A deleveraging would bring about an extended period of debt deflation and miserable growth prospects. Which is, regrettably, exactly what Europe may realistically expect in the years to come.