I am not smart enough to say how, but the sheer amount of work this created across the industry is monstrous. It probably has cost $billions to mitigate, and those mitigations have been slow and ineffective (see: my iPhone still being vulnerable).
In my experience, seemingly random pieces of software, libraries, and programming languages packaging their own CA stores has made this much harder to mitigate than simply running 'apt-get update ca-certificates'. We've practically just had to update every single thing to mitigate this.