I don't know how much better modern drives (and SSDs) have gotten[1], but as someone who started digital hoarding in the mid 90's, on-disk bitrot used to be a massive problem. The amount of my video, audio and pictures that suffered damage was palpable. ZFS offering to fix it was massive selling point and the time and based on personal experience, it delivered.

ZFS also lets you specify number of copies on a single disk. This sounds a bit weird, but as drives suffer block failures far more often than total failures, it's actually surprisingly useful in some situations.

[1] My suspicion is significantly, as storage sizes are now multiple orders of magnitude larger and errors per MB can't have scaled up linearly to match.