A warning would be a step in the right direction. I calculated lately that between 5 and 10 % of the daily SBD in the author reward pool is erroneously converted from SBD to STEEM.
My guess is people just want to power up and they think this is a market order, but it's not. In conversation, people often confuse “convert” with “trade." They mean "convert SBD to STEEM on the internal market or via bittrex" but they just say "convert." So people hear that you can convert and look, there's an option to convert, how convenient.
RE: NEVER EVER USE THE "CONVERT TO STEEM" BUTTON! ALWAYS ALWAYS GO ON THE INTERNAL MARKET