Well, a problem in tech certainly. An alternative possibility (and another problem in tech) could be some mid-level developer could have figured out the problem at the start but because of artificial time pressure to deliver they didn't have the time to, so went with the first bad idea that popped into their head without taking the necessary time to evaluate it.

The fact this had to happen in a hackathon suggests a typical disconnect between management and development (and probably poor prioritization by management). Because development knew this was a problem and how to fix it (evidenced by the fact they fixed it), but it took removing management (aka a hackathon) to give development the space to fix it. And now the company pats itself on the back for having the vision to host a hackathon instead of structuring and prioritizing correctly in the first place so this would just get fixed on the clock.

I do think the author's takeaway about the value of simplicity and pragmatism are on point, but that applies not just to code but to management as well.