I believe we're talking about two separate issues then.
The only hackathons I've participated in are the type I spoke about (mandatory by company for employees) and are the only ones I'm familiar with. In the context of a work obligation, I understand the issues with childcare, etc.
If we're talking about events that are taking place outside of work, then I view them like I would view a running event or concert or any other elective activity: go if you want, stay home if you don't. In that context, I agree with you and hadn't considered that hackathons like that exist outside of the workplace.
Also, I think you're missing the point of the parent post. The point is that the balance of pros and cons of a hackathon is a subjective matter. Some people enjoy their intensity and challenging conditions, others hate the inconvenience. You can observe this for hiking and other demanding hobbies.
Bottom line is that if a hackathon, hiking, etc happens to be a way you love spending your free time, you will want to rearrange your life to participate.