AI can do a good job of this. Summarize content and then searching the internet to see if anyone has commented a summary like that before.

But I suspect such a blog would not be popular.

Rather, let the AI search the web for an idea. If the idea hasn't been published widely in the last 3-4 years, it's a safe topic for a blog post today :)

(Next level: unleash the AI to find such under-posted topics, check them against your list of interests, and offer to you for inspiration.)