>> I've been looking for jobs recently, and I've seen only one job posting that mentions data cleaning as a necessity, whereas the rest only talk about data science and algorithm knowledge, or overall ETL design on the data engineering side. Seems like data set knowledge should be emphasized more.

Actual data cleaning, usually in an automated sense, is more 'data engineering' than 'data science' or applied statistics. Feature engineering and 'massaging' training data is more related to DS but it's understood that this data being consumed by the DS is already in decent shape.