I think it would have been impossible otherwise. It's still annoying with the multiplexed address and data pins in the DIP-40: you have to demultiplex them with latches and transcievers. And don't forget the 8088 (used in the PC) couldn't do data in one clock due to the 8-bit data bus (386SX was similar in the next step up.) Pretty cool for us that the 8086/8 are breadboardable though.
They could've definitely put more shift registers on die and squeezed an 8086 in a DIP-16, but then the support circuitry would become even more complex.
It's worth noting that the trend has been towards (high speed) serial buses in later CPUs, e.g. the Pentium 4 was the last generation to use a parallel FSB; that was replaced with the serial https://en.wikipedia.org/wiki/Direct_Media_Interface
Fair enough. I think the original Datapoint design for what became the 8008 was even entirely serial, including the memory. I guess I should have said it would have been exceptionally more annoying. It's hard enough to get a computer out of it. So it'd be impossible in the sense that they wouldn't have met the goal of getting that relatively easy kit out of it and there wouldn't have been any PC.
