Because in 6 max you run into players like this:
PokerStars 0.50/1.00 Hold'em (6 handed)
Hand History Converter Tool from
FlopTurnRiver.com (Format: 2+2 Forums)
Preflop: Hero is UTG with T[img]/images/graemlins/heart.gif[/img], Q[img]/images/graemlins/diamond.gif[/img].
<font color="#CC3333">Hero raises</font>, MP calls, <font color="#666666">
2 folds</font>, SB calls, <font color="#666666">
1 fold</font>.
Flop: (7 SB) K[img]/images/graemlins/spade.gif[/img], J[img]/images/graemlins/spade.gif[/img], 2[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, Hero checks, <font color="#CC3333">MP bets</font>, SB calls, Hero calls.
Turn: (5 BB) 9[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, <font color="#CC3333">MP raises</font>, <font color="#CC3333">SB 3-bets</font>, <font color="#CC3333">Hero caps</font>, MP calls, SB calls.
River: (17 BB) 8[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">SB bets</font>, <font color="#CC3333">Hero raises</font>, <font color="#CC3333">MP 3-bets</font>, SB calls, <font color="#CC3333">Hero caps</font>, MP calls, SB calls.
Final Pot: 27 BB
Results in white below: <font color="#FFFFFF">
SB has 9s 9h (three of a kind, nines).
Hero has Th Qd (straight, king high).
MP has As Ah (one pair, aces).
Outcome: Hero wins 27 BB. </font>
In full ring most guys will call with crap, here they raise it.