I never said “forbidden”, that’s obviously untenable. Even people I don’t like have the right to say thinks I don’t want them to say; I’m speaking of norms and social pressure.

I’m saying that we should tell those who will wield the power to pound sand when it comes to what powers they should get. Ideally the president should not be proposing legislation, that is not their role in this democratic republic. One could argue that the centralization of legislative agenda making into the executive is one part of why presidential elections are such a high pressure situation these days; ideally that should be handled by the deliberative body and not the executive.

That being said, there is a huge, massive, unbridgeable chasm between the DOJ, who is not only capable but expected to send men with guns to either detain you or legally shoot you if you resist and every other organization you listed. The risks of abuse of power within that specific organization are massive, which is why traditionally there’s supposed to be a bit of a gap between the president and the DOJ to reduce the risk of politicization of the latter.

It seems completely infeasible to me to think that Congress and its staff is capable of drafting reasonable legislation without considerable input from the executive agencies.

I understand the general conflict of interest you are concerned about but that is why there are separate branches. The executive branch can only propose and/or respond to inquiries, they can't actually introduce legislation.

(I'm just going to ignore the rabbit hole of regulatory contruction here as that is another can of worms)

Congress is free to consult various other branches, but that is substantively different from the DOJ proposing legislation. Congress should be in the drivers seat, imho.

And yeah, the devolution of quasi-legislative ability to regulatory bodies is a serious ball of wax that I haven’t managed to formulate a coherent solution to.