Interesting way to plant seeds--fruit and all, but I have a couple of problems with the premise.
First, "if you have old tomatoes in the fridge"...I don't put tomatoes in the fridge. It kills the flavor. (although I suppose if you bought them from the grocery as I did last week they probably don't have any flavor anyway!)
Second, as Carol says, you don't know what you're going to get. I have enough trouble finding space in my garden for the tomato varieties I want to grow that allotting some to an unknown cultivar of uncertain taste and productivity seems a waste of time. Tomato seeds are not that expensive! (But if you think they are, there are swaps available.)