Agree. Its part of the game - and as long as it doesn't get personal I don't see anything wrong with it. Harden can walk the walk. Anyone who says otherwise needs to meet Denzel!
...but that's also why you and your friends are not hyper competitive world class athletes. It's the same reason why there is such a high percentage of athletes who gamble - they want to win at everything. Those people see the rules of decorum and taste a lot differently than the average recreational athlete. It's not my style to trash talk like that, but in my younger days when I played on the best courts I could find with former college players, semi-pro & the occasional guy who made an NBA roster for 15 days, a lot of those guys were nasty competitive and trash talking like this was not unheard of.