fair play exist, but still can be ignored and used in your own advantage w/o breaking any rule as is just an honor thing, some doesn't feel is necessary or significant enough to be used.
regarding AC, this always ends on an agreement of both teams, i don't think we can force people to do it as is not always the case you see here now, sometimes people disconnects suddenly and they don't come back or they do but minutes later, which leads both team to choose restart or keep going. Sometimes while score difference is 1 flag, or few frags (w/e mode is) and 1 minute left, someone of the winning team disappear and doesn't come back after the end of the match. there are few other moments where is complex to make a decision but as i said it ends to both teams to deal with this, which would be easier if none of both teams were selfless.