Coming from a live player:
Limping SB is good to exploit aggresive opponents who raise too much on your limp. It is also good not to bloat pots OOP against aggressive or good post flop players.

Against weak players who fold too much postflop and dont raise much I will just raise more and limp even more speculative hands. (Probably see this more live)

I really don't understand why you would just fold or raise from the SB. You are going to be OOP on every street, which is SUCH a disadvantage. Seriously, what are you going to do when you raise A7o, cbet a dry board and get floated. The pot gets huge in a crappy situation. Limping could have encouraged BB to raise worse trash than yours AND you can maneuver in a smaller pot.

I also don't see why you would fold A7o from the SB either, i
t has too much value as top pair/ ace high etc. Like MCAT said.. why fold a profitable situation.