There are two things that non-experts can contribute in a discussion.

The first and most important is "who is the expert". Out of all epidemiologists and government bodies saying different things, who should we listen to?

Secondly, people have other expertises that may be relevant. Experiments have demonstrated that getting people with a lot of different perspectives together can produce better decisions. I recognize that I'm not an expert in respiratory diseases. But I'm pretty good with mathematics, including graph theory and statistics and differential equations. Someone else may know a lot about how supply chains or small businesses are affected by various policies. Or they may be experts in the psychological effects of various levels of isolation.

I also want to mention shouldn't necessarily underestimate the armchair analyst. It's possible to learn a lot on your own. This ties in with the first point I made above, about who is the expert. Evaluating people based on credentials is one way. It's easy and low effort. Taking into account conflicts of interests and track records will improve your evaluation quality a lot. And for most people it's probably not worth their time to evaluate how credible an armchair analyst is.