Because they were lazy that day and thought they could get away with it. That lack of professionalism hopefully caused some players to look themselves in the mirror, and they should have.
Sacramento Whistle is absolutely the funniest thing. I can't get mad about it anymore. If I get mad I'll just give myself high blood pressure and an aneurysm. It's peak humor. Just a two-decade-long practical joke being played on us by the NBA.