AFAIK this only applies to buying HBD. So there is no off-ramp liquidity - this is one of the main things turning DeFi whales off from buying HBD

Off ramp liquidity comes from the conversion of HBD into HIVE. You can do this yourself (unlike the ability to create HBD at <5% premium, which is essentially a privilege of the stabilizer) using the 3.5 day conversion, or you can sell HBD at a small discount and the stabilizer will buy it and convert it.

As with the other direction, people using the pool don't need to know this. They just need to be willing to sell at a small discount and someone else can arb.