Communication became cheap. Everyone wants to share information. However, people aren't interested in consuming everyone's information.
Commercial social media solved this issues with algorithms that lead to filter bubbles and by prioritizing the ones paying more.
We only have a quota of time to dedicate to our social media. Instead of automated sorting and filtering (elimination) of non-paying information. GNU social gives you powerful manual sorting and search tools.
fake news can still be shared, sometimes non-intentionally.
You should always take everything with a grain of salt and fact check.
That responsibility will always be on your side and that's the wisest option
as any automated mean can lead to mono-culture and any form of central government
can build up to censorship.