There are n-ways to join in a conversation, but the more direct experience you have, the better you will be able to field certain types of discussion. So, experts and expert debaters will dive right in and attack the topic head-on. More timid souls will wait in the wings and hope that someone will say something that they can directly respond to with confidence.

Sometimes you have to be slightly shameless if you want to join in a conversation. Stating an opinion (soap-boxing) does feel a bit like cheating the system. But I would argue its slightly better than standing on the sideline.