I dont understand most of you people. You sound like grumpy old men who dont want any changes. I also dont understand people who said that 3v3 basketball did not work. I had a blast watching this one - high pace game that takes only 20 minutes or so, and there are several games a day - fantastic format for action packed event like the Olympics.
However, the main question for me here is player eligibility. As Namejs correctly pointed out, 3v3 basketball is a legit sport with professional leagues all over the world and athletes who specialize in it. Same with, lets say, beach volleyball. There are no 3v3 leagues, it is not a legit sport yet.
So, what are the scenarios?
1) Do it swimming, skiing, skating style, where same people perform in different disciplines? No chance. I dont think Michael Phelps valued his 100m gold medal more than his 400m gold medal. However, if McDavid has 3v3 vs Poland in the morning and a classic game against Sweden in the evening, we all know which of these games will be a practise. If he even decides to risk fatigue / injury by playing both.
2) Allow anyone to participate except those, who participate in the classic ice hockey event. So, McDavid is busy with the main team, while, lets say, Tavares, who was cut at the last moment, decides to go 3v3. Yeah, Canada, USA, Sweden, Russia, Finland, Czechia will have an unfair advantage with legit superstars. But dont they have it in classic hockey too?
3) Ban professional hockey players from playing 3v3. Countries would be able to ice teams consisting of players from half-professional leagues, but there could be controversy regarding where to draw the line and the quality of play might end up bad.
But heck, I would be glad to watch this fast and entertaining new game when you don't wait 2 days for your team to play just to end up with a 1-0 slog.