Plus one comment:
If you e.g. flash stock Boot/Ramdisk/Recovery (whatever applies to your platform), you loose root (dirty way, but people do it sometimes to circumvent bootloop), however:
- With systemless hosts you are automatically back to your original hosts file (no more blocking ads)
- But without systemless hosts, your hosts file still remains as it was last time updated by AdAway (still blocking ads).
Because in the second case AdAway writes to the real hosts file, in the first case it does not