The HP 2648A terminal also had a "block mode", and the RTE screen editor used it. It was one of the first screen editors I ever used (in 1984). (I had used WordStar on CP/M as early as 1979.)
https://en.wikipedia.org/wiki/EBCDIC
https://terminals-wiki.org/wiki/index.php/HP_2648A
http://www.bitsavers.org/pdf/hp/1000/RTE-A/92077-90039_RTE-A...
Generally this is true. But around this era I used a ton of 3151 terminals on AIX, IBM's version of Unix. They were connected to the RS/6000 line of AIX machines. Good times! These machines, as Unix machines, talked in ASCII to their terminals. There was a whole line of port concentrators which would like you connect something like 32 ASCII terminals to a little block about the size of a modern ethernet router, and you could connect 4 of so of these blocks to a device in the main machine.
The 3151 was designed to integrate with other systems where ASCII was already prevalent.