Nowadays, most compies run their servers on zulu or universal time (formerly called Greenwich Mean Time), without any DST. Thats makes administrating it easier.
That has nothing to do with the issue here - different people have weeked at different times. Nothing can be done about that, because the earth is round, not flat.
the server could consider everone's time zone, but that has ugly side effects: I have still weekend while you haven't, so you lose games against me on time while I don't have to even move at all. Friday night it's reversed of course. Also people could cheat another 'weekend day' out by setting their time zone to the earlest one (australia?) on Friday, so their weekend starts early, and on Sun change it to the latest zone (Hawaii or whatever).
All ugly, so not good.