I currently work in a Data Engineering role and agree with your assessment. At the business I work for, there was no BI or data management processes automation until I joined and wrote all the pipelines (in Python) and queries (in T-SQL). Being comfortable with Python and pandas/arrow (or some other language or ETL/ELT platform), SQL, and working with REST APIs is all usually necessary or helpful, but SQL is ubiquitous. And the most challenging problems for the data mgmt team I'm on involve:
(1) getting datasets from historically siloed data management teams to join with each other cleanly and programmatically — which in my case is a political issue, not a technical one
(2) determining the best way to replace old tabular (Excel) reporting with modern interactive (Tableau) dashboards that refresh from a database — which in my case usually means getting a better understanding of many cross-team business processes, understanding how data management is involved in them, and how data is being used to make decisions and take action
(3) determining how to structure and present this data to them with the least possible friction, and in a way that's the most useful and impactful to them
This is all to say that DE roles seem to vary wildly depending on the domain you work in and the kind of business you work for. But at the end of the day the purpose of the role is to make clean and accurate data available to end users with the least friction and in the most impactful way. And most kinds of data businesses use can be represented by, transformed with, and interacted with using SQL.
There's tons of SQL resources, but I'd love to find some books that cover these deeper issues of politics and business process discovery from a data engineering perspective.