Frequency is generally better, until you start being slot restricted. SYD - MEL are not far behind HND - CTS and are comparable to HND - cough for passengers. Both those ports are serviced by widebodies by both NH and JL (heavy domestic Y config) during the bulk of the day. They typically run less services per hour, but more high density widebodies.
Even today, if we were running more 330 services instead of 737s and either SYD or MEL or ATC sneezes, there'd be a smaller impact across the whole as there's fewer movements so more pax per hour can land (even if its fewer planes).
Problem with that is the domestic terminals have limited gate availability for multiple widebody aircraft, why the A330s always use the same select gates at SYD/MEL (the 767s were easier to accommodate)