> .deb is a really good package manager, and is arguably more sophisticated than RPM.

Perhaps. I wouldn't argue either way, but dpkg still maintains its "data base" of installed and available packages/files as plain text files rather than using a DB format like sqlite (which one might chose for such today) or Berkeley DB (back when). The performance difference is negligible today on fast hosts with NVMe backed storage, but fairly annoying when using lesser machines with slower storage, e.g. RPi with root fs on a SD card.