The peg is pretty good for preventing SBD going too low. It hasn't really dropped that far below $1 in a long time. The problem is the other side of the peg is super weak. In theory the high value of SBD will flow into Steem (because Steem Power entitles you to issue the SBD which is of higher value), increasing the Steem price and resulting in higher SBD issuance, higher supply will bring down the price.
It's a double edged sword. It definitely hinders commerce. However our upvotes are worth what, 5 3.5 times what they say on the page now?
I wasn't aware of the issues getting SBD onto Poloniex. I've been getting decent prices on internal exchange despite that.