Lobbyist being experts is something I've never heard before. They are salesmen, do you want to get your nutrient information from a McDonald's commercial? It may save you time but isn't really helpful.
If you want to outlaw lobbying by for-profit corporations, then they'll just create subsidiary lobbying organizations. The NRA is a 501(c)(4), which is also a tax exempt non-profit designation, and realistically it serves primarily as a lobbying group for gun manufacturers.
"We know you don't have time to dig deep. Here is a summary of the research, and our recommendations based on it."
Edit: I also once had a fairly cynical view of lobbyists. But then some people I know went to work for lobby groups after they graduated. When I looked into the types of lobby groups they went to, they were fairly impressive. Things like advocating for homeless, advocating for people without health care, etc.
Lobbyists often are, and, whether or not they themselves are, are almost invariably supported by, domain experts.
> They are salesmen
Yeah, but they are salesmen who do the public policy equivalent of technical sales, and it's a field where selectivity is high because you are selling to a very small number of very high value customers.