I think it is more like "unable to offer eg elevated weighting to specific VoIP traffic unless that is specifically requested by their users" - which means they can't discriminate between services for their financial benefit rather than because that is what their users want (favouring skype over google's hangout unless Google pay them a wodge of cash, or vice versa, for instance).
They would be able to give weighting to VoIP traffic generally by my understanding, assuming that they can correctly identify the traffic of course, so they can still perform good QoS practise to stop large bulk data transfer (P2P sharing, huge HTTP transfers) causing massively inflated latency for more interactive traffic (VoIP, small HTTP(S) transfers, ...) where that matters.
They would be able to give weighting to VoIP traffic generally by my understanding, assuming that they can correctly identify the traffic of course, so they can still perform good QoS practise to stop large bulk data transfer (P2P sharing, huge HTTP transfers) causing massively inflated latency for more interactive traffic (VoIP, small HTTP(S) transfers, ...) where that matters.