This is done in many places. The problem is that a lot of silicon dies the die costs much more than the package. There’s a limit to how small you can make pins

This is done in many places. The problem is that a lot of silicon dies the die costs much more than the package. There’s a limit to how small you can make pins on a package for manufacturing onto a PCB, so if you need a certain number of pins, you either would need to grow the die (which is expensive) or switch to a packaged part. Mobile phones today largely use chip scale packages that do not use any sort of wire bonding, for instance.