Except manufacturing and cost considerations go exactly the other way. An iPhone 5S entire electronics that make it go is slightly smaller an an average stick of gum.... That's all the "modules" except screen and battery. It's made in one shot my high-speed machines that took about 30 seconds from bare board to operating phone parts.. Parts are so small you'd need a magnifying glass to handle them by hand.

The current situatuion is about as good as it gets. There are enough iPhones sold third parties can copy parts or simply canibalize broken ones for repairs. Apple only updates models once a year, so that means there is lots of effort by third parties because their efforts pay off a whole 3 years of repairs. Fixing individual boards takes $1000+ of lab equipment and 2x what the part is worth for labor.

Even Apple's MacBooks only have one main board that's small as possible. That's why Apple started using REAL glass screens, and metal bodies that can be pealed down for their bare scrap costs. To get the ELECTRONICS metals back is going to require some kind of furnace that can contain toxic fumes and perform exotic metals separation. Even then 3/4 of electronic waste is pastic and F4 circuit board material which is utterly useless except to burn off. That leaves 2/3 of at waste as dirt cheap tin-lead solder and a small bit of super fancy alloys.