More than once I've lost a RAID array during a rebuild. That's what backups are for, I suppose.
This is common because there is often no good way to repair a RAID 5 system which is running in degraded state, and there is often no monitoring to respond to array degradation (if you can’t fix it, why monitor it?)
In other words, RAID 5 does not protect very well against drive failures. RAID 6 is more durable but inefficient (there are systems which are both more durable and more efficient than RAID 6). RAID is generally optimized for implementation simplicity over other concerns.
RAID 10?
So, if you have a RAID 5 array where 1 drive dies, the rebuild process is meant to be able to recreate the missing data on the new drive using the parity data from the rest of the drives in the array. However, if one of those drives has read errors, typically CRC type errors, then the rebuild cannot continue because the data it needs is not available. Bye bye data!!
Also, RAID 5 can achieve higher throughput since the data is split between the number of drives in the array. We used to build RAID 51 volumes which is 2 separate RAID 5 arrays, but then add the 2 volumes as RAID 1 volume so they are mirrored. The system only sees 1 volume with the capacity of a single RAID 5 volume. That was before RAID 6.