[jbandela1]

Apart from networking, the hourglass design is common throughout

Electricity is an hourglass. Coal plants, solar panels, gas turbines, wind turbines, nuclear power plants all produce electricity. This is then consumed by electric cars, computers, washing machines, etc.

LLVM IR is an hourglass. Many compilers and languages produce LLVM IR. This is then converted to many different instructions sets.

I think if you want many-to-many non-coupled relationships, you will end up with some sort of hourglass design eventually.

[shadowgovt]

POSIX is also an hourglass, right? It creates expectations on the part of apps of how the OS is interfaced to and expectations for how an OS is shaped for POSIX-compliant apps to interface to it.

Details may vary, but that baseline makes it much easier to, for example, have emacs on Windows, Mac, and every flavor of Linux under the sun.

[cryptonector]

Interfaces are the narrow waists of potential hourglasses: many consumers, many producers.

Any market is an hourglass too.