A great example is ATF abusing the power to redefine what a pistol/rifle/machine gun are multiple times in the past decade. This leads to people who were previously compliant with the law, with prior written approval from the ATF, now are not compliant with their new definition and could face prosecution. All without any new law being passed, all being done by political appointees and bureaucrats.
The amount and degree of interpretation they are allowed to do is obviously up for debate (and has been litigated thoroughly and repeatedly) but its really silly to say "just do what congress says" as if congress doesn't constantly defer its responsibility for creating regulations to the executive.
It actually turns out that they do get to say this
You want elected leaders who are given zero days to spend time with their constituents?
ATF's job in this case should be enforcing the existing law, not writing new law with no congressional approval and then enforcing it themselves.
I agree that congress did give them some limited power to adjust to changing times, however I believe that has been abused in recent years to enact backdoor legislation via Presidential order without going through the expected legislative channels. That power should be revoked.
It is impossible to have an executive branch that doesn't interpret the law because the law is just a piece of paper. Determining what level of interpretation is okay is already a part of our system. There is no way to just revoke that power without just collapsing the government.
It would be interesting to see a review and evaluation of different law and regulation making approaches with their outcomes.
Maybe a better balance would be to have Congress delegate part of the implementation of regulation, but require them to review any major changes beforehand.
That is the government can create some complex regulation. If you continue to violate their regulation you will get a notice of fine, which you are then expected to put that fine into escrow, if the law is passed you owe the fine, if not you can collect it back (with interest?) in 2 years.
Congress cannot be an expert on every possible regulation that would be needed, that is a good job for hired bureaucrats. However they should be the final stamp on everything those bureaucrats propose.
Congress generally doesn't do this because it simply doesn't have the bandwidth, and so core government functions would become unscalable. But you can certainly vote for representatives who support this idea, and we could see how the results come out.
Then why are lobbyists writing so much of it?
More precisely, the power to pass federal legislation. Anyone can write legislation (I've done it, its fun! [0]), and the Constitution also protects doing this and trying to get it passed [1], but if you can't convince the legislative body with the power to pass it to do so, it has no legal effect.
[0] A couple times as a "what would it look like if we wanted to pursue this" in an state legislative office, other times as part of an extended government-simulation project as part of college coursework.
[1] This is part of the First Amendment right to petition.