What you propose is dishonest.
You are correct in your statement that the big box store will not be hurt.
They only pay for the tools after they are sold, they are held on consignment.
The people hurt by 'weekend rentals' are the consumer, in that the wholesaler/distributor must absorb the cost of shipping the tool to a refurbishing center, evaluating the tool, repacking the tool and shipping the tool back to a distribution center for re-consignment. The big box store bears none of these costs, and the distributors merely pass it on...to us! In your first reply you made no mention of broken parts, substandard tools, etc. You simply suggested a use and return after the job at hand was complete.
I am not calling you dishonest, and I'm sure you always do the right thing, however giving this advice to anyone is tantamount to telling your children it's okay to steal, as long as the one they are stealing from won't notice it.
Shame on you sir!