This sounds slightly political, and it is. Intentionally so.
1. the capacity to recover quickly from difficulties; toughness.
“the often remarkable resilience of so many British institutions”
2. the ability of a substance or object to spring back into shape; elasticity.
“nylon is excellent in wearability and resilience”
Christophe Pettus recently said: Right up until you need it, resilience looks like waste
If you use ZFS, you should know about this issue. For example, in disk mirroring, one might say: why are you wasting a whole disk there?
When that single drive dies, how much would you pay to have a copy of it?
Similarly, with raidz3, figure it’s too much of a waste. What are the chances that four drives might die all at the same time? Pretty remote. It is more remote than 3 drives dead, but that’s why you have resilience.
The same approach applies to many things.