The devil is in the details. You can't turn really a command from the 70s into a webservice because its input are command line options/arguments and not query p

The devil is in the details. You can't turn really a command from the 70s into a webservice because its input are command line options/arguments and not query params or RPC arglists, and its output is probably intended for humans to read or parse easily with a regex/sed/awk. Web services speak in structured data for their input and output over protocols that can't be abstracted as file i/o. Because they're not just files. There are additional semantics and concerns that you cannot abstract away with read/write calls. You also need ioctls, you need send/recv, you need parsers on top to do something useful with the data, and so on. The reason that the simple model dies out is because it's not as useful as it seems in practice.