It’s easy to play a numbers game, but you know what will happen. Some joker will figure out that with the owner resource and namespace, they can jam 100, 500, heck even 1000+ things on another resource. So what is the point? You can ask for your metafields, and if you have 2 or 3 or 7 or some modest number sure, it’s a simple join, la-dee-da, off we go. But you know people will abuse this. And so you are just offloading poor performance from one area to another. And granted, it may bridge certain gaps, it will almost certainly bog down others.
Don’t forget, peoplez can writez terrible codez if you let them, and flush Shopify internal performance down the drain, and so the wiring for this has to be done carefully… so ya.. it’s a nice thought experiment.. but not realistic for reasons probably due to DB structure, and SQL efficiency, and the like.