I think you're missing the point here. The point isn't coding in isolation is good, nor that we shouldn't break our work down into smaller tasks, it's that the developer should be given the responsibility and freedom to decide what those tasks are for their work, not dictated from above.

If I'm responsible for project A, I should be able to make 85% of the decisions for that project. Too often, recently, development organizations make every decision from above, then break that up into miniscule tasks that require no thought from developers.

Hackathons, IMO, are just gimmicks to gloss over a deficient product management group or software architecture. If your organization can't be convinced of the need to spend time on something outside of a gimmicky "hackathon", then something needs fixed.