The only advantage most of these parties have is not having been in a position of power to demonstrate they are at least as incompetent as other parties that have, if not significantly more so.
I guess the upside is that in countries with a multi-party system (happens more frequently without first-past-the-post), they virtually always have to form a coalition, which typically ends up in infighting within a party or between parties. E.g. in The Netherlands you typically need four parties nowadays to form a coalition.