They can make a difference for athletes:
"The data showed significant differences in the oxygen uptake (a way to measure the energy cost of running) in the Vaporfly shoe resulting in a 2.8 percent improved running economy, or the amount of energy it takes a runner to go a certain distance, over the Adidas shoe on average"
https://lifesciences.byu.edu/can-your-shoes-really-make-you-...
But not every runner sees improvement in time. so-called non-responders exist at the elite level but I don't recall seeing any analysis as to why some runners run faster and others don't with these carbon-plate shoes.
[edit] a quick search found this article about supershoes and the range of response - see https://run.outsideonline.com/gear/super-shoe-hyper-responde...
Also the significant benefits that comes from improved post-run recovery with modern super shoes, allowing athletes to run significantly more weekly mileage.