Things like a house fire would presumably destroy a series of optical disks which would make most any in house option non-functional.
Well, it makes any option that only uses a single location non-functional. Having two copies at home and one at a distant location (as recommended by the 3-2-1 backup rule of thumb) mitigates this issue.
Network based backups could also fail to transmit data securely and accurately as well
Absolutely. Though the network is usually assumed to be unreliable from the get-go, so mitigations usually already exist here (E2EE, checksums, ECC).
really any sort of replication solution needs validation of the data is of significant value
Absolutely correct. An untested backup is probably better than nothing but most definitely worse than a tested backup.
and have a way to recover if someone does a ‘sudo rm -rf /’ accidentally.
Certainly something that must be mitigated but this is getting out of “hardware failure” territory now ;)