The passive port/amplifier setup matters because MoCA is carried on high frequencies. Cable return path frequencies are typically below 100 Mhz, MoCA frequencies are well above that (one design band between 400-700 Mhz, others above 1000 Mhz.)

The EMTA port is upstream of the amplifier in these devices. Whether by accident (just doesn't work) or design (actively filters out) the amplifier doesn't propagate back frequencies above the return path, neither the EMTA port nor the input port will see them at all.

These newer models have apparently been modified to fix that. I've also seen suggestion online that they have been changed to better propagate the MoCA frequencies between the amplified ports, which earlier designs may not have done well, especially for the higher frequencies MoCA 2.0 uses.