In my opinion, those site are just advertising for your business.
Also, the interviews are just one part of the site. Arguably the most useful part of Indie Hackers is the forum where people share what they're working on with the goal of getting feedback and advice from other founders.
I bet the interviews get way more traffic than the forums.
For lurkers, it’s the interviews for sure.
I think you're doing a great job growing the community, it has a different vibe from HN and r/startups and I personally do get a lot of value from it, although I'm still mostly interested in the interviews.