The main point is not whether it's free or not but that the main page is a landing page. If you visit Reddit, you immediately see content, you are one click away from reading comments. Registering is optional and comes naturally when you want to write a comment yourself.

To convince your visitors, your site is just a landing page. It requires commitment to an account before it is possible to judge the site.

I don't have the experience to judge if that is a good strategy. But if you want to be the Reddit of podcast discussions, then you should show the discussions to the visitors and only request accounts from those who want to write comments.