Considerable portion of that was early ARPANET work often involving somewhat lacking access to hardware, so I'm it's formative ages internet had a lot of directly attaching teletypes to network ports.
Also one can't forget about TIPs, which provided "phone modem to telnet-like" bridge service in ARPANET.
Another part was how text was the one thing that people had standardise enough between different computers. FTP's ASCII and binary modes aren't about love conversion for Unix, but because "binary" meant totally different things on different hosts (could be 8bit octets, could be 28bit words, could be 36bit words, could be 60 bit, before internet fully settled down there were 40 bit hosts too).
Also people are scared of compilers.
All of that led to cultural bias towards textual protocols
Also one can't forget about TIPs, which provided "phone modem to telnet-like" bridge service in ARPANET.
Another part was how text was the one thing that people had standardise enough between different computers. FTP's ASCII and binary modes aren't about love conversion for Unix, but because "binary" meant totally different things on different hosts (could be 8bit octets, could be 28bit words, could be 36bit words, could be 60 bit, before internet fully settled down there were 40 bit hosts too).
Also people are scared of compilers.
All of that led to cultural bias towards textual protocols