and most of the time, most of the chars used are simply not geared for sabotage that's not 'assault this guy' variation. 
Also, simply no time to, so far that's only used in the Tournaments, where the time between people done fighting and a new one starts is pretty short and there's the case of 'I'll just sabotage my opponent, there's no reason to make things easier for the others.' so they'll wait until the pairing is announced, which is when the next fight also starts.