ok eddie, then explain why bridged output @ 4 ohms is equalivlent to
stereo
output @ 2 ohms.

He already did. It's because the voltage is doubled. By the way, the
scenario you described above is often equivalent (or close), but sometimes
not.

because each channel only sees half of the load from the
speakers

Half of the load? What happens to the other half? The speaker doesn't say
to itself "gee, the amp must be bridged, so I better modify my impedance".
(hey, if amps can "see", then speakers can talk!)