What possible reasons explain the growth in the number of executive department that occurred in the 1900s?

The Development of the Bureaucracy is an effect of popularity of political ideologies which supported state interventionism in economy (especially after WWI) this led to rose of executive branch not only in socialist or fascist ideologies but also inmoderate models of welfare state and social democracy, the criticism of growth of executive branch begin in 19070es (Reagan in uSA Thatcher in UK) but truly exploded in the 21st c.