Because the only way you can guarantee a win is to go over the top with cheating like we saw this time. To go as far as it takes. If you just give candidates an edge, they will win "all things being equal", but that won't stop a wave election.

You don't want anyone to go "wait, these numbers are bullshit" and keep fighting until the truth comes out, because that risks exposing the whole trick. So if giving people a 1-3% edge, or 35k bonus votes, or whatever, doesn't do it, you just have to shrug and try again next time.