You can't control it as a malicious censor who's trying to control what Web sites other people's computers can access just because they're on your Wi-Fi. You can absolutely control it on computers that are actually yours.
Of course, this is not the fault of DoH providers themselves - at worst, they have just made it easier to perform this.
And it's a good thing that DoH is easy, because it helps protect vulnerable people from censorship and surveillance.
They will tell you it is to defeat censorship though and to improve network resilience, because they are deeply committed to having the image of being a champion of internet freedom.
And besides, every browser that supports DoH also lets you pick what server to use, and adblocking DoH servers exist.