I think it comes down to a mix of technical and cultural reasons.
On the technical side, a lot of forum software is bulky and would need a full overhaul to bring it up to modern standards. That means rewriting huge parts of the codebase, redesigning the UI, rethinking permissions, rebuilding editors, adding proper mobile support, and so on. That takes staff and money, and with forums shrinking as a whole, I doubt most of these companies are swimming in extra developers or profit. So instead of major updates, we get small maintenance releases while the core stays the same, which is exactly what you’re noticing when you say forums haven’t changed much since 2015 or even 25 years ago.
But I also think there’s a cultural issue. Forums are often seen as part of the “old web,” and a lot of long‑time forum users like them that way. There’s a mindset that forums should stay simple, stay chronological, stay human‑paced, and avoid anything that feels like social media. There’s merit to that; not everything needs algorithms, reactions, or TikTok‑style dopamine loops. But somewhere along the way, “don’t become social media” turned into “don’t modernize at all,” and that’s where things fall apart.
New generations expect basic modern features: good mobile layouts, responsive design, clean editors, accessibility, and a UI that doesn’t feel like it’s from 2004. The fact that many forum platforms still struggle with mobile support in 2026 is wild to me. There’s a huge difference between rejecting algorithmic feeds and refusing to update the software, so it works well on the devices people actually use.
So to me, it’s a mix of outdated codebases, limited resources, and a culture that sometimes confuses “preserving the old web” with “never improving anything.” And that combination makes it easy to see why forums feel stuck while the rest of the internet has moved on.