I guess the reasons could depend on many factors. However, my past experience with employers is that they wanted to participate in hackathons and community mee

I guess the reasons could depend on many factors. However, my past experience with employers is that they wanted to participate in hackathons and community meetups in order to 1) stay up-to-date with what is new, 2) cultivate a relationship with people that are passionate about building, 3) give back to the community from which they derive benefit, 4) make space for ingenuity and creative thinking, and 5) Recruit/collaborate with the best candidates and companies. While it is true that many of the projects that result from a hackathon are not going into production, in my opinion the learning of new tech, the exercise in fast-paced collaboration, and the fun factor of building obsurd things and sparking creativity do have a value that a company shouldn't shut the door on.