Do you assume that when you shoot your heavy stubber at people, they aren't moving as well before they make a Dodge attempt? 'Cause they actually are, and that's why your chance to hit them is such as such but generally lower than the chance to hit a stationary target.
There's no difference between spraying the room with stubber rounds and engulfing it in burning promethium. Some people will duck for cover for a second, some people will just have the luck to not be in the bullets'/flames trajectory. That's what the BS roll represents for the stubber and what them making Agi tests represents for the flamer.
Then, once it's determined that some people are indeed hit with an attack, they have the right to evade with a Dodge test. Simple.