by leading we hope to fold out 5x or 44 type hands that still have a lot of equity against us
if someone has Qx then we actually don't mind because we have implied odds against that hand

it's kind of a two way bet where we want to make our opponent's range strong instead of weak so when we make our flush we get paid off, and the hands that don't pay off our flush fold the flop

now if a lot of people would call with 5x or AJ in this spot then it's a bad time to bet