That is not true at all. I assume you're trading from an exchange, maybe Coinbase?
- Set up an account at bitshares.org
- Go to deposit, and under Transfer Service select OpenLedger, should be default.
- Then where it says "Please select coin..." pick BTC< /li>
- Right next to that is your hash address, copy that
- Last is going back to where your BTC is and putting that address into the recepient address
Just like that you now have BTC on the DEX. From there you can trade into whatever coin you want that's on the exchange including obviously bitshares. Let me know if you have any other questions.