No particular reason for that, and I know very little about tyres. However, my tyres have not yet exploded, nor have they suddenly and unexpectedly lost grip causing me to slide into a ditch, so I reckon it works OK.
34psi front / 36psi rear works for me but definitely worth experimenting with tyre pressures to see what works for you. Personally, if I increase the rears to 38psi my wife will comment on the harder ride :roll: