I guess the question whether Dylan understood, or bothered to try to understand, the traditions he used and pretended to be a part of, is a "matter of opinion," as you say.
But the question was, why did Ewan McColl not like Dylan. And McColl definitely felt that Dylan abused folk material which McColl valued. Even I heard him say so several times, and many of those who actually knew McColl heard it many more times than that. And Pete Seeger agreed, at least to the extent he cut Dylan's cable with an axe. So that is a legitimate answer to the question, why McColl did not like Dylan. It was because Dylan abused traditional material. And maybe that is also a sufficient answer.