By listening to experts, organisations and impacted people, this group of citizens works together to find common ground and set the policy direction for the politicians to respond to.

I think the idea here is to tamper the expert opinion with real world lived experience.

This is covered in the FAQ, the talk-fest one:

More recently, Citizens' Assemblies have been used by the Irish to navigate tense issues like marriage equality, or by the French in the wake of the Yellow Vest protests. In New Zealand, a group of randomly selected Aucklanders used a Citizens' Assembly to set a course for their city's water infrastructure. Their four recommendations were adopted by the Watercare Services board.