Because the illusion that they used to call "capitalism" is revealing itself for what it really was, i.e. just an illusion.

Socialism (of the authoritarian centralized sort) is state ownership of the means of production.

Fascism is private ownership but state control of the means of production through political and economic pressure, or if that fails by direct edict. The state gets all the benefits of owning the means of production but none of the responsibility, and also gets to pick winners. The winners it picks are generally people aligned with the regime, so over time the business world gets stacked with partisans.

(I'm talking about the economic component of fascism, which usually comes with other ideological components like ultra-reactionary social doctrines and extreme nationalism.)

Capitalism in the free market sense is private ownership and private control, with businesses having a significant amount of independence from the state. This independence is both economic and ideological, e.g. free enterprises openly criticizing or even opposing the political class. Fascism seeks to stamp this out and force business to align with state authority.