I believe this compression was added by a PACS or other system that touched the data. You can confirm this by directly exporting DICOMs from your console. Please check the provenance of your DICOMs to determine the source of this.

I have never seen compressed data stored as fragments except in the example DICOM images. It is technically legal, but it does impact the efficiency of the reading and compression. As you have found, very few tools will handle this data, as the DICOM standard only requires handling uncompressed data. Therefore, while your DICOM images may be technically legal, I do not think these are of archival quality.