But they are eroding our democracy, with the complicity of Congress who has been giving the Executive more power for decades because, IMHO, they are too cowardly to take stands for themselves, so they put it all on the Executive

Oh, I think that's a bit unfair. Trivially, shifting power from Congress to the Executive doesn't "erode our democracy." The President is just as democratically elected as Congress is. That's why I noted that critics of Trump often don't distinguish between (among other things) "illiberal" and "anti-democratic." Having power wielded by the President instead of Congress (or staff) isn't anti-democratic.

More substantively, a huge reason that the Executive has accumulated vast amounts of power is because of progressive efforts to have the federal government do more and more stuff. If the federal government is mostly about making very general laws (and having armies and whatnot), then the legislature is very powerful. But the more you have the federal government running programs and permitting and inspecting and awarding grants and running insurance programs, the more power you have to give to the Executive. Every decision the federal government makes that isn't a law is an action that has to be taken by the Executive. The more decisions you have the federal government make, the more powerful the Executive is.

The reason that Trump is able to do what he's doing is by wielding the massive amount of authority that Congress had to give to the Executive if it wanted to have all the programs that we have. For example, do you want to spend a lot of money on funding research in universities at the federal level? You then have to give the Executive control over billions of dollars and the grant application process to allocate them. Want to granularly regulate environmental permitting and regulation? That can't be done by a legislature - you have to give a lot of power and discretion to the Executive. Etc.

You can't have a weak Executive and an expansive federal government.

The reason that this has kind of worked up until now is that most Presidents wanted to get things out of Congress, so that gave Congress the ability to influence how the President used the power that Congress bestowed. But Trump don't care - he realized that the Presidency already had enough authority for him to do most of what he wants without having to get legislation passed.