Dryer stoped working. How the sock could get inside the dryer blower?

Hello, my dryer stopped working. Master came to fix it and he found that the sock was caught in the blower wheel of the driver. As he explained the ONLY ONE way it could happened is that I dried clothing without the lint filter. Which is not possible since I never been drying clothing without the filter. Can you please tell me is it any other way for sock to get into the blower wheel? And how to prevent that happening? Would like to avoid the same situations in future

Thank you

Lena