As you said yourself, volume sizes aren't exactly the problem anymore ie there is tons of space to store bits these days.
Raid rebuilds take way too long for modern volume sizes.
Raid rebuilds take so long that the likelihood of losing a second drive before completion is very high.
The safety you generally want is redundant copies of checksummed data and metadata blocks.
Btrfs allows you to choose the number of copies of data or metadata separately.
Talking about RAID in the context of btrfs and zfs generally seems to confuse people as it brings in the old expectations and understandings they worked so hard at figuring out for the RAID era.
Rebuilds on ZFS and BTRFS are quite reasonable because most of the time only the data itself is rebuild, not the entire drive as with old-fashioned solutions.
Rebuilds depend on drive size, not array size.
Tripple-parity as part of ZFS allows you to create even larger VDEVS while keeping the risks manageable. Interesting for low-performance archiving solutions.
Raid rebuilds take way too long for modern volume sizes.
Raid rebuilds take so long that the likelihood of losing a second drive before completion is very high.
The safety you generally want is redundant copies of checksummed data and metadata blocks.
Btrfs allows you to choose the number of copies of data or metadata separately.
Talking about RAID in the context of btrfs and zfs generally seems to confuse people as it brings in the old expectations and understandings they worked so hard at figuring out for the RAID era.