While I agree that local stakeholders should generally decide on local issues, the notion that average citizens should be those stakeholders is bizarre. If I was on one I'd have no qualification whatsoever to pontificate over the education system, local policing, public transport, and so on, yet I'd seemingly be in a position where I'd be expected to do just that.
The irony is that Thatcher's wildly misrepresented "no such thing as society" speech made much the same point. People undoubtedly have the best knowledge possible about their own lives so should have as much agency over their own lives as possible. They might also have a decent knowledge of those closest to them. What they usually lack completely is any knowledge of those farthest away.
Heaven knows, Brexit showed us that it's far better to have a good decision than a democratic one.
I can see the point you are making that Joe public might not be qualified to make important decisions but have to say that I dont think it is bizarre at all. If decisions are needed for policing have officers on the assembly if decisions are needed on education have teachers, on health have doctors, nurses, consultants to advise the other members.
I think its a fantastic idea because it makes it a lot more difficult for lobbyists to affect decisions that could have a profound effect on society. I remember seeing an American comedian a while back making jokes about his mate and how he always managed to get people to do what he wanted. He ended the joke saying something like '[Poor language removed], this guy could even sell healthcare to the Brits'. I would argue that we are in the situation we are, not directly because of the Conservative Party but because of lobbyists and large amounts of vulgar money. Even the King is not averse to suitcases full of cash.
Brexit was an enigma and common sense or democracy didnt really have much to do with the decision to leave. I voted to remain but almost voted to leave because I thought that a serving British Prime Minister couldnt possibly write a profound slogan on the side of a big red bus, then drive it round the country and later on actually cut spending on health.
Our country desparately needs change. I'm nearly 60 and never thought I would see the day when if you dialled 999 for an ambulance or police that they might or might not actually turn up, and I think that citizen assemblies might actually prevent this situation occurring. Lets face it, I dont think it could be any worse than what we have now