prohibited to do after mass as it's like a abuse

every time I get a few hundred I get bored and stop playing lol  and then loose my code

those -mode codes were meant for players that have actual experience with games (550 wins+).
In general, by the time you get around 550 wins, you should have come to fully understand the game and not be a douche.

This is just as much a problem with "veteran players" (those with legitimate codes) as it is with players with a hacked code. In fact maybe it is more of a problem with players who save codes and stick with one main account, because they care so much about wins and ELO that they use mode forcing to try to gain unfair advantages. I often see alts with hacked codes using their codes to do -ars and -ssd or even -ars mode, but i rarely see them doing "mode abuse" like -6vs6 mode 40 minutes into the game. That is more likely the behavior of someone on a main account who wants a win no matter what for their precious stats/elo.