Debian popcon is opt-in, first of all.
Q) What information is reported by popularity-contest ?
A) popularity-contest reports the system vendor [1], the system architecture you use, the version of popularity-contest you use and the list of packages installed on your system. For each package, popularity-contest looks at the most recently used (based on atime) files, and reports the filename, its last access time (atime) and last change time (ctime). However, some files are not considered, because they have unreliable atime. For privacy reasons, the times are truncated to multiple of twelve hours.
[1] i.e. the dpkg Vendor field, see dpkg-vendor(1).
So no fucking MAC addresses and machine-ids and harddrive serial numbers and stuff.
They only want package statistics, the point being to have statistics about the popularity of packages, mainly so they can be prioritized for the CD/DVD isos. You know, information that actually has a use, not hardware identifiers that can only be used for tracking purposes.
You don't need this to count unique users. You could just assign a random number on install or whatever. Or even more simply, just run the thing once per month, should be accurate enough. Do they expect the software to just randomly spam duplicate reports? Don't write it that way.
Best case they don't care about collecting minimal data and don't understand that hashed MACs are easily reversible. So incompetent fools with no sensitivity to privacy.
Maybe this should be Manjaro's tagline: Not purposely malicious, just grossly negligent and ignorant.