[creaghpatr]

They tend to serve as subject matter experts when it comes time for legislation to be drafted. It's not practical to expect a 50/60-year old Senator to be able to architect nuanced regulations of social media platforms which didn't exist when he or she was in law school so they outsource the details to lobbyists or similar organizations like think tanks.

[jessriedel]

Well, the senator also has a large staff for drafting legislation.

[creaghpatr]

True, it's an ongoing negotiation between lobbyist groups and the Senator's own in-house experts.