Why is BHVR so conservative with buffing killers?

So what if Ghostface accidentally becomes very strong for a while? There should be killers cycling in and out of the meta over time. I don't understand the reasoning behind letting so many killers languish and the top 5 stay the same for years -- these same 5 killers aren't only a little newer/licensed than killers who have been weak for years

They also don't need any reworks, just adjustments to make them stronger.