I recently did a backup and I could restore this in the another manually, I had no problem
I never said it can’t be done..
Read the first paragraph here https://wiki.mikrotik.com/wiki/Manual:System/Backup
System’s backup file also contain the device’s MAC addresses, which are also restored when the backup file is loaded.
So when you restore a .backup to another device you clone the MAC addresses too…
Anyways, if you prefer restoring a .backup rather than a .rsc its certainly you choice…