Because you need the private keys to be able to install CFW on OFW 3.56+ and nobody has them.
CFW can only be installed on OFW 3.55.
You can install a "mod chip" aka ODE (3k3y) to play backups, but having CFW is more flexible because you don't need to keep the "mod chip" installed, you just use it to downgrade and then take it out. Also, you cannot run homebrew with an ODE.
CECHL 500GB: OFW 2.50 > OFW 2.76 > OFW 3.41 w/ dongle > OFW 3.55 > 3.55 kmeaw > Rebug 4.30.1 > Rebug 4.30.2
You can always use the Like
button if you think my post was useful
Off to my summer vacation, might be AFK for a while... Happy Summer!