Flicker does as advertized, people just misunderstand the description and assume it is massively overpowered.
At 5 points, Flicker increases your chance of causing elemental effects by 30%. This means you cause elemental effects 30% more often. This does not mean that a weapon with 15% elemental effect chance will now have 45%, as that would be a 200% increase, not a 30% one.
What I haven't seen confirmation on is if the same elemental effect can stack multiple times in intensity (i.e. lighting someone on fire twice causes them to take twice as much damage per second from the burning effect), or if it simply re-applies the same burning effect. In the former case, flicker would effectively increase you damage per second due to elemental effects by 30% (though how much it impacts your total damage output would depend on how much damage you do per second from bullet damage vs. the dps of the elemental effect). In the latter case, Flicker would effectively be useless, because any decent elemental SMG is going to be able to cause a DOT effect within half a second most of the time, and doing it .1 seconds faster has no major impact on killing speed.