I don’t want to underestimate the value of good hardware RAID with BBWC implementations when it comes to avoiding problems that aren’t bugs, but are “just the way things are.” For example unclean shutdowns, and especially unclean shutdowns along with a device failure.

There’s a metric ton of really useful information in the man 4 md page that most people probably aren’t aware of because they usually read the mdadm page. http://linux.die.net/man/4/md

Relevant in this case is the Unclean Shutdown section. It’s completely rational for people to think, hmmm, maybe I’d rather get a hardware RAID card that supports BBWC to avoid some of these problems? Plus then you get to use no barriers, resyncs and degraded operation can have much lower performance penalty, etc.