I think the reason they are making that comparison is that there are a lot of other factors that feed into the final numbers. Crime stats aren’t a final determination of the inherent criminality of different groups of people. Things like poverty, arrest rates, and conviction rates all skew the numbers.
With pit bulls, people often get them because they want a dog that’s “tough” and they essentially train (or don’t train) them to be bad dogs. The dog itself isn’t at fault.
Anyone who’s been around a lot of dogs will tell you that small dogs are more bitey. The fact that a pit bull is stronger and can do more damage is also not the dogs fault.