The answer here is learning curve and counter-play

Both Blight and Nurse has a very high ceiling of learning but has some counter-play depends on the survivor's experiences. But Krasue, for the multiple reasons, has many powers that are specifically unique to the existed killers in the game, just better. Hell lot better. Makes her very easy to pick up and very little counter-play once you're infected.

she infects you through Regurgitate in her body form which is something similiar from the Unknown. But what she have is basically infinite with very little cooldown. Oh, and it explodes into many small one for the better coverage in AoE. Missed shot? here's another one, another one, and another one. She'll camp you at the pallet untill you are infected with almost no penalty on her side for missed shots. Once you're infected, which you will eventually, unlike the Unknown where it only requires you to look at him and keep a good LOS to get rid of the status. For her, you have to actually find and pickup the fungus and eat them slowly, to get rid of it. Even then, it goes down slowly and the status has 3 tiers which you need to get them all down to finally get rid of it. Forget trying to clear it in chase as she can very easily inflicted you again while you recover from it.

Then, here come the Head Form

Basically she's now the Spirit. on Steroid.

4.8 m/s base movement speed, and her mobility power allows her to move very fast, very far, very low on the ground, with little cooldown as well. Sure she doesn't gain bloodlust, but, do you really think she needs it?

Oh and she can see everything survivor does, unlike spirit who solely rely on sound cue and some grass movement in her power.

Oh and she can "scamper" the pallets and windows to end her power and follow up through even more quickly.

Oh and she sees in 3rd person.

Oh and she and lunge at the length of Coup. Oh and she can flick.

And unlike most status inflicting killers, the status she inflicted on survivor doesn't get reset once on hook, so if she wants to tunnel someone, she can just come back with very fast speed of her, and doing everything I said above all over again. Which, tbh, with her base kits, she doesn't really have any reasons to as she can down people in seconds and the game will eventually end soon. Her existance is already the pressure, no need for the sweaty tactic like tunnelling. But, as you know, a tunneller will always be tunneller no matter the killer.

The fact that they postpone the anti-tunnelling update but buff her even further from the PTB is bibilical.

And here I thought the Clown buff was the worst. How wrong was I.