Actually, having computer boards with their own CPUs was NOT a modern phenomenon due to excessive computing power. They have always been made, as early as in 19

Actually, having computer boards with their own CPUs was NOT a modern phenomenon due to excessive computing power. They have always been made, as early as in 1980 (without the s), and for good reasons. Some were even a bit unimaginable today: for example, we had Z-80 Softcard (https://en.wikipedia.org/wiki/Z-80_SoftCard https://en.wikipedia.org/wiki/Z-80_SoftCard), a Z80 expansion card made (by Microsoft!) for computers with 6502 CPUs (Apple ][) to run existing business applications written for CP/M, like WordStar. It can also be connected with a modem to utilize its additional processing power to run a BBS server. There were also cards that packed multiple CPUs to implement a poorman (home computer) version of parallel processing. The simplicity of single-task operating systems and hardware architectures of that time allowed multiple independent computers to shift control of a physical computer back and forth. Today it's - pretty much - impossible, but nobody needs it either, you can just run everything simultaneously.