The reality is we are in the Internet Age and th era Social media, where news has to be created for ratings. There is an endless need to generate stories, irrespective of the field, whether sports or politics to grab viewership. Money is generated via clicks on ads.
Football is now the same where social life of a person outside of football is now becoming blurred with the athlete. It probably isn't choosing consciously to become 'entertainment', but it is happening because of the new culture.
These athletes get tried in social media, before actual court and public image dictates how things proceed in a large way by the NFL and other sports. Why would the NFL really want to get in the business of arbitrating these types of matters? It's way more of a cost and headache to them.