For starters, there's no data to back up or combat that claim. Nearly all crash data recorded around the world only tracks a collisions involving a motor vehicles. So while there's a lot of good data regarding when cars hit peds or bikes, there's almost nothing in regard to data when bikes hit other bikes or peds. Given the mobility and general anonymity (no license plate or ID required to operate) of cycling, even tracking down individuals that hit someone is difficult. Cars can sometimes hit and run, but usually someone gets a license plate or car description - or the car is damaged to the extent that it can't leave the scene.
And while the likelihood of death and serious injury increases with mass and speed (ground beef if hit by a semi doing 60mph), most cyclists and pedestrians are hit in low-speed, dense urban areas and suffer head injuries when knocked down and not wearing a helmet.
The solution? Treat them like cars and require cycling licenses, cycling tests, bike registration, mandatory liability insurance, stricter enforcement, taxes, fees, more bureaucracy, and harsher penalties. Sound good, comrade?