saddle bags rattle annoyingly.
stuff in pockets can cause sever injury when crashing.
The former is solved by an old sock to hold everything together
I’ve never seen or heard of the latter?
Did 8 hours on the road bike on Sunday, 0.2l saddlebag takes a CO2, tube, patches, chain links multitool and tyre levers. Back pockets took walet/phone/keys, jellybabies and a couple of spare tubes/CO2.
I took a tiny (1.5l and no storage) camelpack to take additional fluids (not really needed could have managed without or begged some water from a farm if needed) and a gillet, the gillet could have easily fitted in my jersey.
The only times I take a camelpack on short rides now is at night as the batteries tend to drag the jersey one way or the other.