I think most sensible parents and coaches would always support dual or multiple sports because like anything else in life, it’s good to have some variety (it certainly doesn’t hurt anyone).
That said, if you are looking at being the absolute best you can be in any sport or domain, it makes sense that you should spend as much time as possible doing it. People will always pull up outlier stories (he or she played 5 sports until he or she signed their first contract) but the reality is that the majority of elite level soccer players (and I would argue this is likely the case for other sports) only played soccer growing up, or certainly played soccer the vast majority of their time.
It’s a simple thing in my opinion. If a kid spends more time than you doing something, it is almost certain that they will be better than you are. Sure, genetics, opportunity and other aspects might come into it but all other things equal, the kid who spends the most time practicing will likely be better.
Anyone can push an agenda or find an angle. That’s why there is no right or wrong answer when it comes to this subject.