I often see peers struggle with writing documentation because they prioritize it as a separate task. For example they write all the code in a giant PR and then try to go back and write the documentation for everything at once. This creates a much larger more insurmountable seeming goal than if they had broken up the task and written the docs for each piece instead.
Another critical mistake is expecting devs to cover writing the documentation that explains the deep contextual intricacies of the business logic and reasoning for said logic. Big mistake. Your docs should cover the code and how it can be operated. Anything else is why we have project briefs, strategies and other documents and meetings.
So writing documentation isn’t hard. It’s just more and more devs are coming from a willy-nilly-web-search-when-you-think-of-it background with no formal organizational skills or experience.
Most of what is written in doc-blocks above your function should be generated. Everything else is operational information.