Isn't Bedford the one who struggled to break 60 in a 400 m.? Guy got a lot out of what he had.
I would like to posit something revolutionary. It's possible for an issue to be nuanced and not have just one thing that is the right explanation.
For example: Kiptum could be a world record holder because he is unbelievably talented AND he runs a ton of miles AND those miles are made possible by super shoes AND his world record really isn't as fast as we think because of racing in super shoes vs. real shoes AND he is doping (maybe even to the gills).