The fact that, in most situations, one doesn't need professional driving abilities is also not of consequence.
I think people who are critical of the idea of a 10x engineer are missing the point. Of course hiring a 10x engineer is not sufficient to Solve The Customer's Problem. 10x engineers are not fairy dust. However, hiring a 10x is necessary if your customer genuinely needs a bespoke solution, or if you are trying to disrupt an existing tech market.
I would also add that one of the main contributions of a 10x is that they raise the productivity of everyone else (creating tools, providing guidance, simplifying code, etc.). I am not a 10x, but I've worked on teams that have them and teams that do not, and it makes a big difference.
Looking to create a completely packaged toolset, from a custom linux distro, that orchestrates containers and does config management (CoreOS)? You might need a 10x engineer.
Bob went farther than Lewis Hamilton, in a much cheaper car, with no pit crew. Hail to Bob, the 100X Driver!
Your scenario is much the same as the above scenario. Different businesses can extract different amounts of value from programmers. Just like you can't tell a high performance car from a low performance car in a school zone, so some businesses are not tackling hard enough problems to differentiate between programmers. In regards to delivering a CMS, there is not much John Carmack or Jeff Dean could do to distinguish themselves in terms of value to the business than someone who just graduated from Wordpress bootcamp.
In the above scenario, if you are just a run of the mill business, that just needs a CMS to post PR pieces, then Alice is the right choice for you. There is also no point in even discussing 10X programmers because a 2X programmer would be a complete waste of money. If on the other hand, your company is looking to "disrupt" CMS, you want Clyde.