There's another possibility but only because you mentioned SQL specifically. People often use SQL as shorthand for "understand how to manipulate data," and if a new hire doesn't have this skill it can really set a data team back, so interviewers are touchy about SQL. It would be helpful if they clarified if it was the SQL syntax skills or the data manipulation skills they had a problem with. But generally I agree with you that companies should prioritize problem solving skills over technical minutiae.