Yes, that part is true, which is why users should keep local copies of song files (the original ones if higher bitrate) and also back them up locally. I do not personally use or rely on iCloud Music Library as my backup.
However, CONCEPTUALLY, in how iTunes is now designed to work with iCloud Music Library, your iCloud Music Library is the primary music library. For example, song files stored locally are referred to in current iTunes as "downloads" from your iCloud Music Library (even if they're your original song files that were never "downloaded"). The command to delete a locally stored song file is now Remove Download, not Delete. The command to Delete is now used to delete song from your iCloud Music Library.
Your iCloud Music Library is accessed equally from multiple computers and devices associated with your Apple ID. There is functionally no primary computer or device, as defined by the system. Users can treat a particular computer as their main computer (like we do), but that's only a user decision, not part of the system design.
DRM is no longer applies to Matched music in Apple Music. Only music from Apple Music library has DRM
Not according to this document, which still appears to be current
iCloud Music Library: Understanding differences between Apple Music and iTunes Match - Apple Support
"Using Apple Music - ... We make these matched songs available to your other computers or devices in high quality 256 Kbps AAC, and they can be played on them only while your Apple Music membership is active." [DRM]
"Using iTunes Match - ... all of the songs that we matched or uploaded using iTunes... can be downloaded DRM-free (if matched) or in their uploaded form and are yours to keep. These songs can continue to play after your iTunes Match subscription ends." [no DRM]
Basically, if you only have Apple Music, matched songs downloaded from your iCloud Music Library are treated the same as direct downloads from Apple Music streaming service. A distinction that many Apple Music subscribers (who sometimes intentionally delete their original locally-stored song files to free up space) do not understand.