The reason, why its common to start open jamming deeper blind vs. blind is, that good players will defend a lot against min-raising from SB, so you dont get the same fold equity, as you do from BTN or CO. If you then raise big, you lose to much, when they jam on you, and if you limp, this will also get attacked a lot. So against good aggressive players open jamming is often the least bad option from SB seat, simply because it takes their options away. They can either call or fold, and if you jam correctly, there is nothing, they can do to outplay you.
As for your hands, if he spite call you with Q8o or K3s, this is not the end of the world, if you fold K7s, but if you hold 98o, it sucks quite a bit. So K7s is a pretty mandatory jam, whereas 98o is a hand, that can be folded, if the opponent is a calling station. Or both hands can be limped, if he is passive and will allow that to happen.
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