Yes I would agree. When cancelling the original flight passengers are presented with a choice of a refund minus the penalties in the fare rules, or the voucher. But as a service gesture it's a one time hit, rather than a way to permanently avoid the fare rules of an originally inflexible ticket. Subsequent cancellations effectively bring you back to that original choice but with only the refund minus the penalties now available. The new ticket and the underspend part of the voucher are still linked both together and to the orignal fare rules in that respect.