If you ignore the highly politicized lobbyists, you'll find that expertise is one of the main things lobbyists provide to politicians.

"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.