Hackathons represent everything that's wrong with development. People put no time in to really think about an idea (just go with what sounds 'best' in the 15 minutes at the start), no time to plan (code the first approach that sounds like it'll work), an unhealthy environment without sleep, exercise or decent food (pizza and beer are ace, but they're not healthy), and as the article says, usually no buy in from managers or team mates afterwards. Plus they tend to be exclusionary because anyone with a family or responsibilities, or who needs a good night's sleep, is effectively excluded from a team because they're going to miss a big part of that 24 hours.
It's quite incredible that a health startup like Oscar Health would actually encourage hackathons.