I have probably 300 hours in duel and I do feint probably a bit too much. Any above average player rarely if ever falls for a feint spam and any player who knows you feint can just swing and hit. All in all if you fall for feints you just need to practice the game more.
Let's put it this way, what is there to be lost if people got chat banned for example for saying racist things. Surely the vast majority of people don't want to see that anyway.
TDM and siege are great for the casual player base but like what has already been said here there is a large portion of the player base who have spent thousands of hours in warband playing the more competitive side of things and these game modes don't quite scratch that itch.