Pot Limit Betting Preflop

[lucky_mf]

The sb only gets to raise to $6 for the reasons you described.

Lucky

[mrpotatoh7]

Does that not cause a disadvantage for the small blind to raise?

[SheridanCat]

I suppose, but keep in mind that since everyone will be in the small blind at some point, everyone will have the same disadvantage roughly the same number of times in a session.