There's a long legacy in America which has led to the expansion of the executive branch. It didn't start with Trump. Almost every power he's abusing was recklessly laid down in prior administrations/congress. FDR caused lots of controversy with how he acted and there was a pull back from executive power, including administrative laws currently slowing Trump down.

There's lots of other examples, such as the various emergency powers, including a large string of them for terrorism during Bush and expanded during Obama.

I've been posting about this issue on HN long before Trump was in power and plenty of journalists were documenting it.