I don't think the coupon book is specifically designed or targeted towards Flybuys members - it is more of a Coles coupon leaflet with a 10 week promotion. I guess if you shop at Coles nearly everyday (as I do), the system would recognize you as regular shopper at Coles and therefore, a candidate for the promotion.
Just adding a datapoint. We previously used to receive the 10-week promotion coupon book I would say every cycle, but prior to the VFF partnership didn't really use any of the coupons at all. Since we received the last coupon book and post Flybuys-VFF partnership we utilised the the offers quite aggressively (and the email offers for in-store bonus points). Since the partnership we've converted 50K FB points over to earn 25K VFF points (during their 15% bonus promo). We now also have another ~12K points earnt and waiting for the next 15% promo (assuming they'll do that again).
Anyway since this more aggressive use of earning bonus FB points we have not received the latest coupon book I would say for the first time since we started getting them. Also the email offers have become harder to achieve (3 weeks of $140 a week shopping to trigger a bonus - previously was 2 weeks and a smaller spend). It will likely be the case that our shopping at Coles will drop off and we'll be targeted with easier-to-achieve promotions down the track.