Earlier quoted context omitted.
How do you know you're not propagating bitrot over time? Feels like a binary here and there may accumulate mismatching checksums over the years from bad hardware or some filesystem error... Not to speak of malware. All it takes is once... Feels a lot safer to do the system- and package installation from scratch and then rsync/dd only /home and /etc.
ZFS is how.
There've been a bunch of integrity-impacting send/receive bugs in zfs over the years.