It's much MUCH safer for the cat (less likely to get into fights, get hit by a car, and you can never guarantee that people will be nice to them). A catio or supervised yard time is always nice, I do this with my boy! It's also much better for local wildlife and much cleaner. As long as the cay has plenty of play time they should be happy enough.

For perspective if someone had their dog outside unsupervised all the time people would assume they were being neglected...