But off-topic: I wonder what computers would look like if there _were_ arbitrary restrictions like that. What directions would we have pursued in microarchitecture, distributed systems, etc etc if there was a regulation capping clock speed or number of transistors, or a rule that made it illegal to have asymmetric network connections?

In fact that probably would have already made the case for speed restrictions, as every multi-thousand-knot container ship created its own tsunami. There have long been speed restrictions on canals at a few miles an hour to avoid erosion.