I very much doubt that M/F are not getting routes that have more than a single service because the WW crew will turn on them. What a horrid assumption!
Maybe it is just due to the fact that WW crew need two nights at some of these destinations, as do the pilots but that M/F don't and that would add to confusion for the ground staff, having two sets of crew operating with different slip patterns. It may well be confusing for scheduling also.
I heard that M/F crew and WW crew got on fine in Hong Kong in the bar recently and a M/F CSM posted how helpful the NRT crew were to his positioning HND crew on their way to Tokyo, explaining the service to them all.
Trouble is with forums is that sometimes people guess why thing are but get it wrong.