I think we'll have to "agree to disagree" here Pyanepsion My experience with importing Word DOCX files into InDesign has, on the whole, been very good with little, or no alterations necessary. Importing raw text files of even RTF just creates a lot of work, IMHO. As I said before, Affinity Publisher's handling of Word DOCX files is "OK" as at least all the paragraph and style definitions are included - it's just that the fonts, sizes etc. can (but not always) be altered, which is a simple matter of correcting the definitions.
Generally, this is much better for me when dealing with entire books. My current book is about 300,000 words and this will probably end up nearer 400,000 when completed. I'm not sure how large, or small, your client's documents are, but for a book this size having some of the work done is better than none at all