I'm not so naive to think that Democratic Party staffers don't have a revolving door system like the GOP staffers. I worked as a legislative coordinator in my former union's PAC for a few years. I went up on the hill and locally and met with dozens of staffers. I was lobbying them just like professional lobbyists do. For the most part, staffers aren't career government employees. They have to be knowledgeable about the legislative areas they cover. Quite often that knowledge and expertise is gained in the private sector. If anyone is expecting their members of congress to only draw their staffers from unions, advocates, and academics, they are probably going to be disappointed. Maybe a few like Bernie Sanders do, I don't know. Most don't. The difference is that you'll find less of them with the Democrats than you do with the Republicans. The Republicans don't have any staffers that come from unions, environmental advocates, consumer advocates, minority organizations, etc. The Republicans represent business interests, and specifically big business interests exclusively. They aren't in it for anyone else.
Liz Fowler is a member of the bar AND has a Ph.D from John Hopkins. With her resume, she could work anywhere she wants and command a high 6 or 7 figure salary. Instead she has spent about 10 years working for the federal government making less than a member of congress and still does. That doesn't look like an industry plant to me, perhaps to others it does. Now I'm sure the insurance industry had a seat at the table. It would also be naive to think they didn't. But I don't see them authoring that law. There's too many things in it they were vehemently against.