Those mechanisms aren't textual, they are byte-sequence based.
It turns out that many text-based protocols are more popular than binary/object alternatives. The penalty for textual redundancy is negligible/acceptable for many of them. Where not, Unix allows people to use unix/create new mechanisms to implement specialized protocols (rpc, protobuffers,...).
OK, I probably misspoke by claiming it put an emphasis in protocols, but I think it's fair to say that Unix does emphasize component integration by sharing data instead of trying to integrate through a common runtime.
I do think that having everything be (mostly) text is helpful though. It's true that the data formats are often poorly specified, but that is compensated for by the fact text is a format that has a very rich set of tooling. text editors, regular expressions, parser-generators, etc. all make it possible to capture, analyze, and manipulate the text data exchanged.
Perhaps a better example of protocol-based integration would be the internet. It has it's flaws as well, but it's also enabled collective engineering projects on a vast scale.
Unix doesn't put a strong emphasis on protocols. It just says "everything is text, except when it's not". It's not very helpful.