One possibility is to require of everybody to disclose real identity to the moderation team, with an option to disclose or not disclose it to everybody; rigorous formulation of rules about which kind of behaviour may then imply that the identity must become public is not necessary in my opinion.

If this requires lots of technical work, and not only on MO but on the whole SE network, still I believe it is worth it, because of several serious reasons already well explained in answers here.

In any case I think discriminating among "suspicious" and "nice" users by requiring different things from them is a very harmful idea.