That’s exactly it: we already have this in the form of the lobby industrial complex. Except it is possibly quite a bit worse because if you stay in Congress for a long time and form a trusting relationship with your lobbyists who by the way also pay to your reelection campaign or support you in other ways, over time you get to accept their expert opinion with less skepticism. If a lobbyist has to start over every 2 years, they can’t sink their teeth as hard into you. And I doubt many congresspeople are experts on most subjects on which they write laws. Some have economics degrees. Some are doctors, some are lawyers. Very few engineers, it seems.

If you wanted an alternative system: you could always have a professional group of law writers and a professional group of law opposers try to present arguments to a large assembly of law jurors. If they can’t get 2/3rds majority on a law, it doesn’t pass. This is better than something like direct democracy where everyone votes on an issue because you can’t get the voters’ attention on any one thing for more than a few minutes or a few hours at the most (except a small fraction for whom it is their life for a while). In this law jury setup you can properly brief them.

You could have some other body of professional governors who do things like emergency resolutions and maybe basic budget stuff but anything beyond that goes to the assembly for approval. You could create a new assembly as often as every 6 weeks and process a batch of laws at once so that you really rotate out the jurors before they can be influenced. And selection of law writers and law opposers can be something that is reviewed by this kind of assembly too, or just some large pool of professionals who are chosen at random for any given period of time and given the power to present before the assembly. A lot of options here for how to amortize bad behavior such that over the long haul it averages out to close to zero.

Assuming, arguendo, that corruption is somehow not a factor in your scenario, it still doesn't account for ignorance. Consider that jurors in jury trials have one binary decision to make based on the facts and law given to them. They don't need to decide if the law is just (in fact that's explicitly NOT what they're supposed to do). They don't need (and are not supposed) to decide if the situation is fair. That happens elsewhere by folks trained to consider these things. Jurors in jury trials literally apply the law they are given to the evidence they are presented. That's it. Even this burden is often more than a lot of folks can wrap their head around.

The legislature, however, is not there just to nod its head when they think something is a good idea and voting no when it's not. Even if we were to create a space for exactly that, all we've done is push the fallibility to those who are doing the work to write and revise law--but now they're pitching to those off the streets who don't know anything about governance! If anything, lay congresspeople would magnify, not reduce, the problems we have with our current system.

I am definitely not going to argue with almost any of what you said. My main point is that democracy as we have it now clearly has flaws and maybe exploring ways to amend it to work better isn’t a terrible idea. Again, Ireland successfully used randomly selected assemblies to decide in major legislation. Perhaps a state like California that loves doing direct referendums and as a result has referendums decided in part by how successfully the campaign around the given issue is can benefit from a longer deliberation by people who are not known ahead of time.

Currently, the Congressional staff is mostly recruited and retained by the congresspeople, and they become the experts in many situations. They can also be retained by the committees, in which case they are often more non-partisan. They do have some ability to influence the debate, but they usually do not frame it.

If we had national assemblies by sortition every 2 years, I would worry that the the tail (the current structure of Congressional support staff) would wag the dog. A better system would need to be designed to enable good decision-making.