I should print this out, laminate it and wave it front of all those people who are bound to laugh at 10SC per month, say it won't even get you from Red to Silver or say it's cheaper to earn them flying... because the Flybuys SCs earn is not mean to replace your SC bounty of flying, it's there to do exactly what you've mentioned – to 'top up' an account which is just short of the necessary SCs to bump up into the next tier or retain an existing tier.
We've all seen people asking about how to close that gap of 20-50SCs and until now it's just been a quick status run. Now they can turn their shopping across the course of a year into a small but steady trickle of SCs which could well obviate the need for that last-minute run.