The spread on SBD and Steem on exchanges, especially the internal exchange, is typically very high. I've seen it as high as 17% !! If you want to do it quickly, having to change to Steem adds a huge cost to the process. Using the 'convert to steem' option takes a week.
Edit: For example now on the internal exchange the spread is 1.35%. The order books at those prices are also incredibly thin, so slippage is involved for even small amounts.
That's actually quite some spread, or quite a long wait. Thanks for explaining, wasn't aware.
The large spread is the only way that market makers can make money providing liquidity, given that Steem is a highly inflationary coin and they're taking on the dilution risk, and it is not intended as a coin for commerce, so regular market participants don't contribute to the liquidity as they would in Bitcoin or similar.