I read the article. I see how much published work on the problem is mentioned, and where is it published. In this case, not much. If a mathematical problem is really hard, and really important, of the type to reasonably qualify as a "25 year old problem", you will see a lot of partial results, many different approaches, connections to other ares of mathematics, a lot of work by many people. Nothing like that happened here.
What I said is that "very few people cared" is a better description than a "25 year old problem". It is better because it better aligns with the facts presented in the Wired article above and other similar sources, due to reasons above. Nothing here is a guess.
