That's a good point. My claim is probably too specific to software developers. Maybe I should have said "technical users" instead.
I was paraphrasing from the Donald Chamberlin quote in the last section of the linked PDF[1]:
"When Ray and I were designing Sequel in 1974, we thought that the predominant use of the language would be for ad-hoc queries by planners and other professionals whose domain of expertise was not primarily database management... Over the years, I have been surprised to see that SQL is more frequently used by trained database specialists to implement repetitive transactions such as bank deposits, credit card purchases, and online auctions. I am pleased to see the language used in a variety of environments, even though it has not proved to be as accessible to untrained users as Ray and I originally hoped."
Where the original Sequel authors took their Sequel spec and implemented it on real hardware + software, with interfaces for both "non-technical" ad-hoc queries as well as integration with PL/1 and COBOL for more technical users.
I have "non-technical" in quotes since in that 1970/80's timeframe, you had to be pretty technical to even have that label.
I don't have any evidence to back this up but my guess is that the underlying key/value store & cursor APIs were probably the intended way for programmers to interact with the database. SQL came out in the 1970s so every ounce of performance was important.
I was paraphrasing from the Donald Chamberlin quote in the last section of the linked PDF[1]:
"When Ray and I were designing Sequel in 1974, we thought that the predominant use of the language would be for ad-hoc queries by planners and other professionals whose domain of expertise was not primarily database management... Over the years, I have been surprised to see that SQL is more frequently used by trained database specialists to implement repetitive transactions such as bank deposits, credit card purchases, and online auctions. I am pleased to see the language used in a variety of environments, even though it has not proved to be as accessible to untrained users as Ray and I originally hoped."
[1] https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6359709