We do make exceptions. The reason we made that rule was when the price of Steem was high and we were getting 700 people per week entering and many were karaoke and were really, really bad. We had to make that rule just so we can keep the focus on musicians who play an instrument.

The focus of Open Mic has always been for musicians who play musical instruments, but if they are really good singers we do make exceptions. Also,  @vanne has entered before with a musical instrument accompanying her which is one reasons we allowed this exception.