The issue was that none of the trio of shell scripts/awk/sed could stand alone, so the "language" by necessity consisted of all three tools. You'd write the main loop in shell and use awk and sed when required.
Remember, this was 1987—25 years ago, before bash and other modern shells, and with much more primitive versions of awk and sed. Nor was the web available to look things up.
Writing shell/awk/sed scripts back then was awful, no matter how much the Bell Labs folks touted its superiority.
When perl showed up on comp.sources.unix it was an incredible breath of fresh air. I downloaded and built perl based on its claim to replace shell script/awk/sed programming and Larry Wall's reputation as the author of rn [1], my preferred newsreader for usenet. Perl lived up to its billing and was an enormous improvement for writing scripts.