That's one of the big reasons people share for sure. Another reason that can't be underestimated is that, sometimes, it just feels good to talk about something you've been pouring your heart into in obscurity for years.
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 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.
Wholeheartedly agree with this. The hardest thing about being a solo founder is the loneliness. In times of joy, in times of grief, it's just you. Sharing your successes and your failures with a group of supportive entrepreneurs as you plod along is the next best thing (or maybe even better) to having a co-founder.
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.