Does commenting before registering on forums have any draw backs?

I'm redesigning a forum and one of the issues we earlier faced is the drop off rate during signing up. One of the reasons we did find was there being too many questions asked by an admin during this process and we're addressing that.

The current flow is such that if a user needs to comment on a topic: 1. the user needs to register 2. then validate email ID 3. come back to comment

We want to prevent the user from having to come back to the page to comment and were wondering if having them commenting before registering made sense? And should we even venture down that path?