#1 Poor example to youngsters
This is the most important, as the next generation is the thing that matters at the moment. Those who look up to the likes of Ronaldo and Messi, who want to be them are focused on what they are winning on their own.
The more individualism is celebrated, the more kids will try to do too much on their own or feel unappreciated when performing the other roles vital in a successful team. That is not what football is about, where there’s a role for every kind of footballer and them all working as a unit in order to win.
Promoting being the best solo player creates the wrong kind of examples for kids to look up to. They should all want to be Ronaldo because he does the right things and prepares in the right way, rather than because he wins all these magazine covers and Ballon d’Or awards.