Hackathons make a lot of sense to the people that profit directly from it and/or whose job is little more than babbling buzzwords and "getting the team on fire!!", which you only have time to do if you're not bashing your brains pulling all-nighters programming (no objection in doing this for fun, obviously)
They're great for MBA-bots who want young, naive developers to crank out a barely functional proof-of-concept for free.