A quick refresher on the details of how congress actually goes about their day-to-day plus the roles of the various permanent government and de facto government

A quick refresher on the details of how congress actually goes about their day-to-day plus the roles of the various permanent government and de facto government organs, shows "expertise doesn't scale" isn't really a problem. If it was, the whole thing would have come toppling down ages ago. So the libertarian argument is only "it's hard to do well", not "it's impossible". I'll leave you to find your own references to get a detailed picture, but in short two basic forms of organizing do a lot of the work: big teams/staff for each congressman to help out, and special interest committees and caucuses. On top of that at least some take the idea of "representation" somewhat seriously, so if they need to know about a topic they're not experienced in, they tend to meet with supposed experts in those topics (which can come from a dedicated pool, lobbyists, state university department, and occasionally private industry owners or high level employees) for information and sometimes policy recommendations.