As people already said, there is little point on talking about hypotheticals, since those properties are inherent...

But there are tools that can distribute a program over a network, and let your functions run at any node with the right capabilities "just like" (the network allowing) if it was local.

This is another point that the microservices pushers miss. It's a solved problem, and can be done in a much better way than what they push around.

But network calls ARE inherently flakier and slower. What good does it to imagine they weren't?

It helps demonstrate where additional investment and development might be warranted. If we have hit a physical limit in networking, then that is one thing - but if we are only hitting an artificial limit because our technology and infrastructure is not sufficiently advanced - then this problem is actually showing an opportunity.

As an architect you have to sometimes ignore constraints to understand if the final picture you would assemble makes any sense. If the final picture you assemble makes sense, then working backwards through the limitations, to find out, are these really limitations or are these opportunities to innovate?

That's my thought as to why you would imagine they are not a limitation. To aid in brainstorming, innovation and identify opportunities for improvement, or alternative solutions you would not have seen if you simply accept the bottleneck as a given.

As GP said the network is inherently flakier and slower and yes, we are very close to the physical limit.