It's less about the specific content, and more about continuing to push something without good science behind it.
For example: I think X is true, I cherry pick data to back up X and publish a book on it. This book gets a lot of attention and is good for my career, but it's based on bad science and misleads people. This is a theory I identify myself with along with my success and my own career, if its ideas are invalidated that reflects negatively on me and my abilities (and potentially the ability to support myself). There's an incentive to rationalize or continue pushing the bad science which slows down figuring out what's really true. This has happened a ton of times throughout history.
In this specific situation the benign case is people sleep more and it doesn't matter (or it helps), in the pathological case people are anxious about their lack of sleep and it negatively effects their life or they sleep more than they personally need and it turns out over-sleeping is co-morbid with depression and causes other issues.
In the general case popularizing bad science has knock on effects that make it harder for people to get funding to study ideas the contradict the popular, but incorrect zeitgeist of what's commonly thought to be 'true'. It can also lead people down rabbit holes that can take a long time to crawl out of and make it take longer for people to understand what is actually true.
You can't just hand wave this away by saying "I know X is true, therefore it doesn't matter if the data is a little problematic. X is true and it's good for people to know that". A lot of times X turns out not to be true, not to be entirely true, etc.
For example: I think X is true, I cherry pick data to back up X and publish a book on it. This book gets a lot of attention and is good for my career, but it's based on bad science and misleads people. This is a theory I identify myself with along with my success and my own career, if its ideas are invalidated that reflects negatively on me and my abilities (and potentially the ability to support myself). There's an incentive to rationalize or continue pushing the bad science which slows down figuring out what's really true. This has happened a ton of times throughout history.
In this specific situation the benign case is people sleep more and it doesn't matter (or it helps), in the pathological case people are anxious about their lack of sleep and it negatively effects their life or they sleep more than they personally need and it turns out over-sleeping is co-morbid with depression and causes other issues.
In the general case popularizing bad science has knock on effects that make it harder for people to get funding to study ideas the contradict the popular, but incorrect zeitgeist of what's commonly thought to be 'true'. It can also lead people down rabbit holes that can take a long time to crawl out of and make it take longer for people to understand what is actually true.
You can't just hand wave this away by saying "I know X is true, therefore it doesn't matter if the data is a little problematic. X is true and it's good for people to know that". A lot of times X turns out not to be true, not to be entirely true, etc.