That last bit is why I'll never do one again.
Hackatons are commonly used as a way to take credit for & reap the benefits of another person or team's work, without attribution or compensation. And oftentimes, a promising hackathon idea will be "improved" by management & added to the creator's workload with tight deadlines (because the hard part is already done!) -- even if they don't necessarily agree with the "improvements".
Yep, a way to get free work by pretending its fun, most corpos immediately turn around and do this.
It's also funny to me because of how they try to show its a treat to the engineering staff, and then railroad them as soon as they can to implement the half baked idea.
The truth is that most management don't ever get beyond half baked ideas and so trying to push you to make low quality crap is often their only move.