It's not impossible to exchange high amounts of HBD but it takes patience. You can't just do it in one go. The stabilizer exchanges $100K per day and sometimes multiples of that without moving the market much (if it did move the market, it would stop trading, and it often doesn't). It also does depend on market conditions to an extent, but this is not rare. This, of course, is HIVE-HBD. If you are coming from another stablecoin, fiat, another crypto, etc., you have to buy HIVE first, then get it on chain to use the internal market. HIVE has decent liquidity, but you have to do two trades, and you can't buy too much HIVE at one time unless you want to take additional HIVE price risk. So overall it is high friction.

I agree utility would improve with more convenient and consistent ways to access liquidity.