Why fintech specifically?

Destructive operations are both tempting to some devs and immensely problematic in that industry for regulatory purposes, so picking a tech that is inherently incapable of destructive operations is alluring, I suppose.

I would assume that it's because in fintech it's more common than in other domains to want to revert a particular thread of transactions without touching others from the same time.

compliance requirements mostly (same for health tech)

Because, money.