> The datasets aren't usable in the same way

I strongly disagree, especially since this tool aggregates both posts and comments. While they don't measure the exact same thing, HN posts and comments are quite similar to searches from the standpoint of "What are people interested in finding more about and discussing" - stories that get popular usually have a lot of comments, thus boosting relevant terms, while posts about topics that don't trend score low because they don't get any relevant discussion comments.

Heck, just try it yourself - I compared "blockchain" to "OpenAI" with this tool, and got a predictable result (blockchain had some spikes up until the late teens, then OpenAI took over with the launch of ChatGPT). Interestingly, the Google Trends plot for these two terms looks very similar.