Unless I am misunderstanding the voucher system, ie to be used in lieu of cash and would accrue a avios and tier points as per normal cash booking, surely this would be preferable to receiving avios back as one wouldn’t be subject to the very limited pool of availability and more importantly would receive avios and tierpoints. For example if my F to Singapore were to be cancelled I would receive a voucher amounting to the cash cost of this flight so I can just book a new flight which would take me to gold. I can’t see it happening so am assuming I have misunderstood the voucher scheme, but I can dream!