Rating not changing by winning on time

So in regular online chess games winning on time before a decent amout of moves have been made means your rating doesn't change. What about tournament games? why doesn't it change in those games? thanks

the games were rated ones

yes but what difference does it make if moves have been made or not?

If less than 4 moves have been made (I think) then chess.com scores the win as a win by forfeit. Winning by forfeit does not change your rating, even in USCF and FIDE.

oh... ok even in correspondence?

Yes, less than 4 moves and won/loss.on time won't affect your rating

hmm ok 

Should be written down somewhere in the rules on this site, but I can't find it at the moment